Home Explore [Sky & Telescope magazine in March 2009] Sky & Telescope... -Humans to the Moon

[Sky & Telescope magazine in March 2009] Sky & Telescope... -Humans to the Moon

Published by divide.sky, 2014-07-21 23:19:15

Description: President Bush delivered his well-publicized speech
outlining a vision for future human exploration of the solar system. He
described how NASA would return people to the Moon and set up a permanently occupied outpost. Later crewed missions would venture to Mars.
I can’t think of a more exciting prospect than seeing humans walk on Mars
in my lifetime, and I suspect many S&Treaders share that view. The Mars rovers have been an incredible success story, but a field geologist could perform
in a few days the same tasks that have taken Spirit and Opportunity five years
to accomplish. Moreover, if microbes are eking out an existence on the Red
Planet right now, it will probably require a human presence to root them out.
But to pay for NASA’s Constellation Moon program, President Bush called
for money to be taken from other NASA programs. When I worked at NASA’s
Goddard Space Flight Center from February 2007 to May 2008, I saw firsthand
the toll that budget cuts are taking on NASA’s

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1 - 43

Robert Naeye Spectrum Founded in 1941 by Charles A. Federer, Jr. and Helen Spence Federer The Essential Magazine of Astronomy E D ITOR IAL Humans to the Moon? Editor in Chief Robert Naeye Senior Editors Dennis di Cicco, Alan M. MacRobert Associate Editors Tony Flanders, Stuart J. Goldman Imaging Editor Sean Walker Editorial Assistant Katherine L. Curtis Editors Emeritus Richard T. Fienberg, Leif J. Robinson Senior Contributing Editors J. Kelly Beatty, Roger W. Sinnott In January 2004 President Bush delivered his well-publicized speech Contributing Editors Edwin L. Aguirre, Adrian R. Ashford, Greg Bryant, Paul Deans, Thomas A. Dobbins, David W. Dunham, Alan Dyer, Sue French, outlining a vision for future human exploration of the solar system. He David Grinspoon, Paul J. Heafner, Ken Hewitt-White, Johnny Horne, E. C. described how NASA would return people to the Moon and set up a perma- Krupp, David H. Levy, Jonathan Mc Dowell, David Ratledge, Fred Schaaf, Govert Schilling, Gary Seronik, William Sheehan, Charles A. Wood nently occupied outpost. Later crewed missions would venture to Mars. Contributing Photographers P. K. Chen, Akira Fujii, Tony & Daphne Hallas I can’t think of a more exciting prospect than seeing humans walk on Mars AR T & D E S I GN in my lifetime, and I suspect many S&T readers share that view. The Mars rov- Design Director Patricia Gillis-Coppola ers have been an incredible success story, but a ﬁ eld geologist could perform Illustration Director Gregg Dinderman Illustrator Casey Reed in a few days the same tasks that have taken Spirit and Opportunity ﬁ ve years PUBL ISH I N G to accomplish. Moreover, if microbes are eking out an existence on the Red VP / Publishing Director Joel Toner Planet right now, it will probably require a human presence to root them out. Advertising Sales Director Peter D. Hardy, Jr. But to pay for NASA’s Constellation Moon program, President Bush called Advertising Services Manager Lester J. Stockman for money to be taken from other NASA programs. When I worked at NASA’s VP, Production & Technology Derek W. Corson Production Coordinator Michael J. Rueckwald Goddard Space Flight Center from February 2007 to May 2008, I saw ﬁ rsthand Ad Production Coordinator Kristin N. Beaudoin the toll that budget cuts are taking on NASA’s astronomy program, as relatively IT Manager Denise Donnarumma inexpensive missions are delayed or never funded. Great discoveries about the VP, Consumer Marketing Dennis O’Brien Director of E-Media Stephen Singer origin of the universe, the physics of black holes, and the existence of life-bear- Fulﬁ llment & Renewals Manager Dominic M. Taormina ing planets are being put on indeﬁ nite hold. In addition, good space-science New Business Manager Adrienne Roma Marketing Coordinator Kim Ciommo-LeBlanc programs are being raided because of huge cost overruns in missions such as Credit Manager Beatrice Kastner the Mars Science Laboratory (see page 17), the James Webb Space Telescope NE W T R AC K ME D I A L L C (JWST), and the Stratospheric Observatory for Infrared Astronomy (SOFIA). Chief Executive Ofﬁ cer Stephen J. Kent Executive Vice President / CFO Mark F. Arnett I’d love to see American astronauts return to the Moon (or preferably, visit Corporate Controller Jordan Bohrer a near-Earth asteroid). Even in its years of peak funding, Constellation will Ofﬁ ce Administrator Laura Riggs consume only a minuscule fraction of the federal budget, so there’s no doubt Editorial Correspondence: Sky & Telescope, 90 Sherman St., Cambridge, MA 02140-3264, USA. Phone: 617-864-7360. Fax: 617-864-6117. E-mail: the U.S. can aﬀ ord it. Economic studies prove that government spending on [email protected]. Website: SkyandTelescope.com. Unsolicited research and development is a great way to create jobs. High-def TV images of proposals, manuscripts, photographs, and electronic images are welcome, but a stamped, self-addressed envelope must be provided to guarantee their people on the Moon will motivate more kids to study science and engineering. return; see our guide lines for contributors at SkyandTelescope.com. Still, I wonder if future Congresses will have suﬃ cient political resolve Advertising Information: Peter D. Hardy, Jr., 617-864-7360, ext. 2133. to make this happen. Congress is not funding Constellation adequately Fax: 617-864-6117. E-mail: [email protected] right now, even though its peak funding lies years into the future. America’s Web: SkyandTelescope.com/advertising national debt is approaching $11 trillion (about $35,000 per capita), but the Customer Service: Subscription inquiries: [email protected] Change-of-address notices: [email protected] actual debt is much larger when one takes into account entitlement spending Phone toll free: 800-253-0245. Outside the US and Canada: 386-597-4277. promised to retiring Baby Boomers. And the debt will undoubtedly soar even Product inquiries: [email protected] Product phone toll free: 888-253-0230. higher to pay for massive bailout and economic-stimulus packages. When it comes time in the next decade to pony up the big money to send Subscription Rates: US and possessions: $42.95 per year (12 issues); Canada: $49.95 (including GST); all other countries: $61.95, by expedited humans to the Moon, will Congress be in a mood to deliver? Where’s the money delivery. All prices are in US dollars. going to come from when a large portion of the federal budget will be paying Newsstand and Retail Distribution: Curtis Circulation Co., interest on the national debt? How long will foreign investors be willing or able 730 River Rd., New Milford, NJ 07646-3048, USA. Phone: 201-634-7400. to loan the U.S. government the hundreds of billions of dollars it needs annu- No part of this publication may be reproduced by any mechanical, photographic, ally to sustain such large budget deﬁ cits? Can a nation with such a staggering or electronic process, nor may it be stored in a retrieval system, transmitted, or otherwise copied (with the exception of one-time, noncommercial, personal use) level of debt be serious about setting up lunar colonies and launching astronauts without written permission from the publisher. For permission to make multiple photocopies of the same page or pages, contact the Copyright Clearance Center, to Mars? What role might international partners, or competitors, play in future 222 Rosewood Dr., Danvers, MA 01923, USA. Phone: 978-750-8400. Fax: 978-750-4470 Web: www.copyright.com. Specify ISSN 0037-6604. funding decisions? I’d be interested to hear your thoughts! The following are registered trademarks of Sky & Telescope Media, LLC: Sky & Telescope and logo, Sky and Telescope, The Essential Magazine of Astronomy, Skyline, Sky Publications, SkyandTelescope.com, http://www.skypub.com/, SkyWatch, Scanning the Skies, Night Sky, and ESSCO. Editor in Chief 8 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Lettersters Let Star of Controversyaaaar of Controversy Pluto: When Will It End?uto: When Will It End? St St St St St St St One sure sign that a ﬁ eld of study is in ne sure sign that a ﬁ eld of study is in I I wish to respond to Michael Molnar’s wish to respond to Michael Molnar’s CK / XRSX Focal Point essay concerning the Star of decline or has stagnated is endless squab- FocalPoint essayconcerningthe Star of clineorhas stagnatedisendless squab- bles over taxonomy and nomenclature. I Let’s hope this gets settled soon, before the Bethlehem (December issue, page 112). would think that there are enough new and legislature inserts itself into the debate! Though Molnar and I have come to diﬀ er- S&T: CASEY REED; HAND: ISTOCK / XRSX fascinating discoveries in this golden age I agree in principle that Pluto should be ent conclusions about the Star, it’s unfor- of astronomy to warrant an end to the moot demoted from the rank of planet, but the tunate that he had to so malign me and and silly squabbles over Pluto (December International Astronomical Union needs my research as presented in the December issue, page 34). I’d rather see in-depth to tighten up the deﬁ nition of “biggest 2007 issue (page 26). I’m congruent with articles about orbital “clearing” or the ﬁ sh in the local pond” before everyone decades of biblical scholarship in both spheroidicity of various bodies in the solar can sign on. Pluto and its kind are just too stance and methodology (such as Birth system than this tiresome hash over Pluto’s diﬀ erent — qualitatively and quantitatively of the Messiah by Raymond Brown and categorization. Enough already! — to be considered in the same league as The Acts of Jesus by Robert Funk and the Marcus Honnecke planets (or asteroids). Such a major deﬁ ni- Jesus Seminar, as well as older and newer North Park, CO tion (also applying to other star systems) scholarship). [email protected] needs much time and care, and is not I ﬁ nd it alarming that he considers something to dash oﬀ in a few hours at his word on the subject ﬁ nal, as if one There’s no debate. In 3rd grade, I learned the end of a meeting. astronomer can undo 150 years of biblical that Pluto was a planet, so it’s a planet! As Wouldn’t it be fun to eavesdrop on a studies by assertion, especially without for your experts, may I remind you what galactic survey ship as it reports on our addressing the arguments for ahistoricity. ﬁ nancial shape we’re in courtesy of the solar system: “Four planets and a bunch Rather than attack him personally, “experts”? End of discussion! of debris.” though, I have addressed his charges Jeﬀ rey B. Krieger Phil Perry against me and the lines of evidence for Greer, SC Bearsville, NY his position on my blog. I show them to [email protected] [email protected] be weak at best and contradictory to his 50 & 25 Years Ago Leif J. Robinson March 1959 made last fall with the 200-inch telescope on tigators are beginning to Patchy Air “One of the most perplexing Palomar Mountain. . . . consider what will be the problems of artiﬁ cial satellites has been the “To test for the presence of plant life, several next major step in optical observed irregular or semiperiodic ﬂ uctuations astronomers have examined the spectrum of instrumentation. Evidence of their periods, which cannot be explained Mars for the characteristic bands of chlorophyll. is accumulating that giant on the basis of gravitational theory. Luigi G. The failure to ﬁ nd such bands, however, does not space telescopes, made up Jacchia, Smithsonian Astrophysical Observa- rule out the presence of vegetation. . . . from a number of separate tory, who ﬁ rst discovered these anomalies, “Dr. Sinton applied a new criterion. All large mirrors on independent satellites, are a realistic now presents deﬁ nite evidence that they can be organic molecules can absorb infrared light of prospect that can potentially provide research explained by changing atmospheric structure about 3.5 microns wavelength. . . . tools of extraordinary power. . . . — variations in the density of the highest “Not only was the presence of the infrared “Such a device . . . could achieve diﬀ rac- regions of the atmosphere absorption deﬁ nitely conﬁ rmed, but Dr. Sinton tion-limited resolution of millionths of an arc — caused by variable solar established that it occurred in dark regions . . . second. . . .” radiation.” and was absent or weak in bright areas. . . .” NASA’s Space Interferometry Mission is in Oops! “The best evidence We now know that Mars is as barren as a development, with a launch no earlier than 2015. yet for the existence of brick, at least as far as plants are concerned. Its main objectives include searching for Earth- plant life on Mars was mass exoplanets, determining the size and shape reported by William M. March 1984 of the Milky Way, ascertaining precise stellar Sinton, Lowell Observa- Microarcsecond Resolution “As the space masses and luminosities, and mapping the distri- tory, from an infrared study telescope comes closer to reality, various inves- bution of dark matter. 10 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Letters desired conclusion. I also make the point that the Star was probably not a historical Write to Letters to the Editor, Sky & Telescope, event. My blog and further discussion can 90 Sherman St., Cambridge, MA 02140-3264, be found at http://tinyurl.com/adair1108. or send e-mail to [email protected]. Aaron Adair Bay City, MI [email protected] that supported the case that the evangelist was trying to make. I became interested in the Star of Bethle- Accepting this conclusion changes the hem back in the 1980s and since that time quest to one of searching for what could I have studied the literature extensively. So have inspired the story. what was the Star of Bethlehem? The fact In AD 66, some years before the gospel that there’s no generally accepted answer was completed, two important events took in itself says a great deal. place: the visit of magi to the Emperor However, one of the strangest things I Nero and the apparition of Halley’s noticed is that in many cases once astrono- Comet. Did Matthew use these events to mers delve into the subject, they seem help get his points across? to become seduced by the attractions of Rod Jenkins astrology and begin to believe that signs in Bristol, United Kingdom the sky can foretell royal births. This may [email protected] have been a belief back then but it doesn’t make it valid. I can’t go along with this line, and believe that the only possible valid scien- For the Record tiﬁ c conclusion is that the story was sim- ✹ Galaxy NGC 4649 is in Virgo ply made up. It’s a story that was crafted (November 2008, page 20). to be compatible with the beliefs of the ✹ The photograph of nebula NGC 6960 day, a story that the author was convinced on page 103 of the December issue was taken reﬂ ected what must have been, and a story in collaboration with Stefano Cancelli. –40° PUPPIS Z VELA 8 h Facing South ON THE WEB WHAT’S UP AND WHERE? YOUR PERSONAL SKY CHART OBSERVING FOR ALL SkyandTelescope.com/letsgo What will the sky look like from your backyard tonight? How did it look from Timbuktu on your PRETTY PICTURES birth date? With our Interactive Sky Chart, it’s easy SkyandTelescope.com/gallery to create your own customized map of the heavens for any date, time, and location. Then print it out SELL YOUR STUFF SkyandTelescope.com/ and take it with you under the stars. classiﬁ eds SkyandTelescope.com/skychart CELEBRATE ASTRONOMY 400 YEARS OF THE TELESCOPE We know you haven’t forgotten, but we’re going to keep reminding you anyway! The International Year of Astronomy is well under way, and as new projects come online, you’ll ﬁ nd them on our website. SkyandTelescope.com/IYA2009 12 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

News Notes T To get astronomy news as it breaks, visit o ge S S Sk SkyandTelescope.com/newsblog.yan Watching Tycho’s Supernova — in Reruns On November 11, 1572, the Dan- later “Tycho’s Supernova” is just a wispy, light of the explosion faintly reﬂ ecting ish nobleman Tycho Brahe spotted a expanding remnant of debris, best seen from interstellar dust clouds many brilliant new star in Cassiopeia. In the at radio, infrared, and X-ray wavelengths light-years oﬀ to the side, far enough following days it became brighter than (lower left). From indirect evidence, away to give the light an additional 436 Venus, shone through the blue daytime astronomers have deduced that the years of travel time. sky for two weeks, and took 16 months supernova must have been a Type Ia, the The spectrum of the reﬂ ected blast to fade from sight. It convinced Tycho kind that results from the runaway ther- clearly identiﬁ es it as a Type Ia super- that the realm of the stars was not monuclear explosion of a carbon-oxygen nova of the “normal” variety seen at its changeless and eternal, white dwarf. Because time of maximum brightness. Spectral prompted him to become their intrinsic lumi- evidence also suggests that the blast an astronomer, and even- nosities are well known was asymmetric. The team was, in fact, tually helped set modern SUBARU TELESCOPE / NAOJ (by and large), Type Ia able to model the outburst in detail. It’s astronomy in motion. supernovae have become the ﬁ rst supernova in our galaxy to be More than 400 years crucial “standard candles” classiﬁ ed by its outburst spectrum. for measuring large And like time travelers, astronomers cosmic distances — and will be able to observe the supernova from those, the chang- over and over again whenever they ing expansion rate of the want, for centuries to come — for as universe (February issue, page 22). long as the light echoes remain visible. The color image at left, of the rem- Astronomers have dreamed of car- nant as it stands today, combines X-ray MAX PLANCK INSTITUTE FOR ASTRONOMY / CXC / SPITZER supernova alongside Tycho, but that (red) views with a near-infrared image rying spectrographs back in a time (blue, green, yellow) and mid-infrared machine to 1572 and observing the of the ﬁ eld stars. hardly seems possible. The extremely faint light echoes Now, in a sense, it is. In September (inset) are located well oﬀ to one side. 2008 a team from Germany, Japan, They required deep exposures by the and the Netherlands observed Tycho’s 8.2-meter Subaru Telescope on Mauna supernova exploding in 1572 via a 436- Kea in Hawaii. year-old light echo. They identiﬁ ed the Betelgeuse Making Waves Akari reveals the shock fronts in more Bow shock The Japanese Akari satellite, launched in detail. A Japanese team reports ﬁ nding 2006, conducted all-sky surveys at a wide that Betelgeuse is plowing by 30 km (19 Motion of Betelgeuse range of infrared wavelengths from 1.7 to miles) per second through an interstel- with respect to the 180 microns. These surpassed the previ- lar ﬂ ow that is coming from the region of interstellar medium ous gold standard for far-infrared surveys, Orion’s Belt and Sword. Betelgeuse itself Betelguese the all-sky mapping done by the Infrared is blowing oﬀ a thick stellar wind at about Astronomical Satellite (IRAS) in 1983. half that speed. The clash of these ﬂ ows Akari also examined speciﬁ c targets in produces a hood-shaped shock front that depth, including the red supergiant star appears about ½° across, the apparent Bow shock ISAS / JAXA / T. UETA & OTHERS Betelgeuse. IRAS had already discovered diameter of the Moon — corresponding that Betelgeuse is creating a shock wave to 3 light-years at Betelgeuse’s distance of as it plows through an interstellar cloud. roughly 640 light-years. 16 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

A Very Oddball Comet probably remnants of an ice sheet that Do all comets originate in our solar sys- covered the planet’s midlatitudes during tem, or have any come from other stars? colder climes. Since then they’ve been Undoubtedly, stars with planetary systems capped by dust, insulating them from expel trillions of comets in their youth to direct sunlight. roam loose through the Milky Way, as our In the image at lower left from Europe’s own early solar system must have done NASA / JPL / UNIV. OF ARIZONA / MOLA TEAM Mars Express orbiter, a mountain in east- — and still is doing occasionally. But no ern Hellas is surrounded by apron-shape observed comet has ever had anything ﬂ ows of the type found by Mars Odyssey’s close to the excess velocity expected for radar to contain abundant ice. one of interstellar origin. A Lowell Observatory astronomer now up what appeared to be slight vestiges Martian Mega- suggests another possibility. Periodic of eroded shorelines around the plains Rover Delayed Comet Machholz 1 is currently in a 5.3- in Viking images. But higher-resolution year orbit highly inclined to the plane of images from later spacecraft revealed little However, Mars the solar system. David Schleicher found more, and the idea lost favor. exploration is not that it is remarkably depleted in carbon Now scientists report that there might going to keep up compounds compared to 150 other comets be something to the ocean idea after all. its expected pace in studied and, in fact, contains hardly more Again the evidence is subtle, this time in the near future. Due than 1% of the the geochemical signatures of the rocks to technical problems NASA / JPL cyanogen (CN) themselves. Odyssey’s gamma-ray spec- and cost overruns, NASA has postponed that comets nor- trometer ﬁ nds more potassium, thorium, the launch of Mars Science Laboratory, a SOHO/LASCO CONSORTIUM He suggests the higher terrain that surrounds it. Water agency, from this October until 2011. and iron in the putative seabed than in mally contain. top-of-the-line “ﬂ agship” mission for the that Machholz Mars Science Laboratory will be the ﬂ owing out of the southern highlands largest and most capable rover yet to would have leached these elements from 1 could have formed in a par- ticularly cold region, or could have lost its the planet’s ancient crust and deposited ramble across the Red Planet — assum- ing that further cost overruns don’t kill it them in any long-lasting ocean. CN through some kind of heat processing The map above combines Mars’s topog- entirely. MSL will be a long-duration mis- — or could be from another star system raphy with a color overlay of potassium sion, operating for two years and powered where carbon was deﬁ cient. abundance (red and yellow) where the day and night by the radioactive decay of But other astronomers note that an northern lowlands (left) meet the Elysium plutonium. Its ambitious payload of 10 interstellar comet ﬂ ying into the solar highlands (right). instruments includes a laser-and-camera system would almost certainly escape combo, dubbed ChemCam, that can vapor- capture. More plausible, says comet expert . . and Buried Glaciers ize bits of rocks up to 30 feet away and Paul Weissman (Jet Propulsion Labora- Hidden in Plain Sight deduce their chemical compositions from tory), is that Machholz 1 formed in the spectra of the resulting puﬀ s of vapor. solar system’s cold, distant Oort cloud Meanwhile, detective work on data from — unlike most short-period comets, which Europe’s Mars Express orbiter has found Mineral Evolution come from the closer Kuiper Belt. a glacier’s worth of ice just under a thin on a Living Planet In the image above from the SOHO veneer of topsoil. This normally wouldn’t Observatory, Comet Machholz 1 (upper be news — Phoenix landed atop a thinly Earth’s evolving biosphere has shaped left) swings close by the Sun on January 8, disguised slab of water ice, and previous the makeup of not just our atmosphere, 2002. The white circle outlines the Sun’s work suggests that buried ice is abundant but the planet’s complement of miner- disk behind the larger occulting mask. for hundreds of miles beyond bothof the als as well. Researchers at the Carnegie Venus shines at lower right. Martian polar caps. But the new ﬁ nd lies Institution ﬁ nd that the mineral kingdom at south latitude 45°, much closer to the has “co-evolved” with life, and that up to Mars’s Oceanic Past. . . equator than thought possible. Tens of two-thirds of the 4,000 known minerals miles long on Earth today can be directly or indirectly NASA’s Mars Odyssey orbiter has found and up to a linked to biological activity. new signs that the vast Martian northern half mile (1 Most of these life-related “rock species” plains are an ancient seabed. In the late km) thick, resulted from Earth gaining an oxygen- 10 km 1980s Timothy Parker, a Mars specialist the stealthy rich atmosphere starting about 2.5 billion (6.4 mi) at the Jet Propulsion Laboratory, turned glaciers are years ago, originally due to photosynthesis NASA / JPL / JOHN W. HOLT & OTHERS SkyandTelescope.com March 2009 17 C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

News Notes Mission Update Jonathan McDowell by blue-green algae. Without ongoing pho- tosynthesis, free oxygen could not persist. The group’s work suggests new ways that extrasolar planets might show spectral Juno: Return to Jupiter to within 5,000 km (7% of a Jupiter radius) evidence for life that exists in the present from the tops of the clouds. It will make 32 NASA’s second New Frontiers mission, or that existed in the distant past. orbits during its one-year primary mission. the Juno probe to orbit Jupiter (S&T: The current plan is then to crash Juno into September 2005, page 24), is moving into Jupiter’s atmosphere. New Eyes on the its construction phase. In 1995 NASA’s Galileo orbiter dropped Cosmic-Ray Sky a probe into Jupiter’s atmosphere, Dawn on Track to Asteroids Scientists from many countries gathered which destroyed it when it was 1% of After a little more than a year in space, at the foothills of the Argentine Andes the way to the planet’s center. To probe the Dawn probe has completed the main last November to mark the completion of the deeper interior, Juno will skim close phase of using its super-eﬃ cient (but low- the Pierre Auger (oh-ZHAY) cosmic-ray above the cloudtops and use remote power) ion engine to help it on its way. sensing methods. By measuring slight On October 31, observatory. Its 1,600 water-ﬁ lled detectors, variations in Juno’s orbit, researchers will 2008, the engine spread across 1,200 square miles (3,000 map Jupiter’s gravity ﬁ eld well enough to was shut down square kilometers), are designed to detect reveal the distribution of matter inside the after using 72 ultrahigh-energy particles striking the top planet. Juno’s JIRAM instrument (Jovian kg of xenon of Earth’s atmosphere and trace back their Infrared Auroral Mapper) will determine NASA / MCREL propellant and cosmic origins. The fastest of these par- the composition of the lower atmosphere thrusting 82% ticles, mostly protons, can carry the kinetic down to where the pressure is 7 times Dawn will ﬁ re its xenon- of the time since energy of a well-pitched baseball — up to 10 Earth’s surface pressure. The MWR ion engine (blue exhaust December 2007. million times the punch of particles in the (Microwave Radiometer) will allow Juno streak in this artist’s Dawn’s initial biggest accelerators on Earth. On average, to infer the temperature proﬁ le all the way concept) to work its way orbit around the only one of these down to 200 times Earth pressure. into orbit around Vesta. Sun was 1.0 by superparticles hits a Particles-and-ﬁ elds instruments 1.62 a.u. at its closest and farthest points, square kilometer of named JEDI (Jupiter Energetic particle but the ion drive enlarged the orbit to 1.22 the upper atmosphere Detector Instrument), WAVES (Plasma by 1.68 a.u. A small tweak with the ion per year (S&T: March Wave Instrument), FGM/SHM engine three weeks later adjusted Dawn’s 2008, page 24). (Fluxgate Magnetometer/Scalar Helium track for a ﬂ yby of Mars in February 2009, The project went Magnetometer), UVS (Ultraviolet which will send the craft into an orbit that online in 2004 with PIERRE AUGER OBSERVATORY Spectrograph), and JADE (Jovial Auroral stretches out to 1.8 a.u. The ion drive will about half its detectors in place. By late Distributions Experiment), together be needed again to get Dawn as far as 2007 researchers had already found that the with JIRAM, will characterize the its ﬁ rst target, the asteroid Vesta, whose most powerful “baseball particles” appear magnetosphere and aurora. And the closest point to the Sun is 2.1 a.u. Dawn to emanate from areas having galaxies with JunoCam imager will return the most will reach Vesta in 2011, map it from orbit, active galactic nuclei: ultrabright objects detailed close-up images of the Jovian and then take oﬀ for Ceres, which it will clouds ever seen. begin orbiting in 2015. powered by supermassive black holes. A second ﬁ eld of detectors, which the Juno is expected to launch in August 2011 for a roundabout, ﬁ ve-year journey HST Servicing Mission team would like to build in southeastern Colorado, would cover the northern sky. including an Earth ﬂ yby in 2013. Once at After many months of delay, the long- The project records ultrahigh-energy Jupiter the probe will take up an elliptical awaited servicing and upgrade mission for path around the planet’s poles, dipping the Hubble Space Telescope (October 2008 cosmic rays in two ways. The photo above cover story) is set for launch May 12th. The shows one of the 1,600 detectors that Juno will be the ﬁ rst fuel tank and boosters for the servicing records “air showers” from high-altitude outer-planets probe collisions. On the hill is one of four build- to use solar panels mission were assembled at Kennedy Space ings where ﬂ uorescence detectors watch instead of nuclear- Center in early December. Meanwhile, powered thermo- engineers at Goddard Space Flight Center (at night) for simultaneous glimmers of light in the upper air. ✦ electric batteries. To rushed to get Hubble’s replacement gather the weak solar command data processor ready for ﬂ ight. energy at Jupiter, the panels will span a Contributing editor Jonathan McDowell To read more about any of these re To circle 20 meters (66 NASA / JPL provides updates on more missions at www st stories, go to SkyandTelescope.com and ories, go feet) across. .planet4589.org. se search for the keyword SkyTelMar09. arch for 18 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Scientif c Breakthrough Exoplanets Imaged Two teams of astronomers of astronomy’s holy grails. At Last have ﬁ nally achieved one FOR MOST OF ITS HISTORY, the study of extrasolar used Hubble’s coronagraph to blot out Fomalhaut’s blazing planets has been rife with false alarms. Because of the pinpoint of light. Observations spanning several claimed big discoveries that later withered away under years in visible light revealed that the object, close scrutiny, astronomers have tended to greet major known as Fomalhaut b, is moving with the new developments with a healthy dose of skepticism. star on the sky (meaning they share a Such was the case during the past few years when- common proper motion), conﬁ rming ever astronomers announced the ﬁ rst direct image of its physical association. Better yet, an exoplanet. Since these claims involved images taken in 2004 and 2006 show Robert Naeye fairly massive objects orbiting very far orbital motion. from their host star, scientists wondered The object is currently situated at a if these were bona ﬁ de planets or heavier “failed stars” whopping 119 astronomical units (a.u.) from known as brown dwarfs. Fomalhaut, about four times Neptune’s distance But last November 13th, with considerable media from the Sun. Fomalhaut b resides just inside a dusty fanfare, two independent teams published new exoplanet debris disk (reminiscent of our Kuiper Belt) that is eccen- images in Science. For a variety of reasons, one or both tric and oﬀ set from the star. The planet is presumably of these claims has a good chance of going down in the shepherding this disk gravitationally and thus probably history books. follows an eccentric orbit. Using the Hubble Space Telescope, a group led by Paul Kalas and his colleagues cite two lines of evidence Kalas (University of California, Berkeley) imaged a magni- that Fomalhaut b is indeed a planet. First, it’s too faint tude-25 object orbiting Fomalhaut. Kalas and his colleagues to be a brown dwarf. Not only is it dim in visible light, the mighty 10-meter Keck II and 8-meter Gemini North telescopes failed to detect its infrared glow. Kalas and his colleagues argue persuasively that Fomalhaut b’s faint- ness, coupled with the system’s estimated 100- to 300-mil- No data lion-year age, means the companion cooled oﬀ so quickly Dust ring that it contains no more than 3 Jupiter masses. And as Kalas also notes, “A brown dwarf could not sit so close to the belt without completely disrupting it by gravity.” Location of The other group, led by Christian Marois (NRC Scattered starlight Fomalhaut Herzberg Institute of Astrophysics, Canada), employed Gemini to image two pinpricks of infrared light 1.72 and FOMALHAUT, DISK, AND PLANET What looks like Sauron PAUL KALAS / STSCI / NASA / ESA 2004 2006 image of Fomalhaut. A coronagraph blocks the bright light of this from Lord of the Rings is actually a Hubble Space Telescope 1st-magnitude star. The space telescope’s exquisite resolution captured a surrounding disk of dust, and a faint object orbiting just inside the ring. Images taken in 2004 and 2006 clearly reveal 22 March 2009 sky & telescope orbital motion. The planet’s orbital period is about 870 years. C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Solar System 50 a.u. Sun Sun 25 a.u. Orbit of Neptune K u i p e r B e l t 125 a.u. 100 HR 8799 System 75 50 25 a.u. HR 8799 HR 8799 Orbit of Planet d Orbit of Planet c Orbit of Planet b K u i p e r B e l t 130 a.u. 125 100 75 Center 50 Fomalhaut System Fo Fo Fo 25 a.u. Fomalhautmamamamalhlhhauauaua tttlhlhauuaaooomamamalhlhauaa tt of disk Fomalhaut Orbit of Fomalhaut b S&T: CASEY REED K u i p e r B e l t 0.96 arcseconds from HR 8799, a magnitude-6 star in Are these objects low-mass brown dwarfs, or planets? Pegasus. Later images at Keck II conﬁ rmed these as Marois and his colleagues point out that all three objects orbiting companions, and revealed a third object only 0.62 are going counterclockwise around the star, and appear arcsecond from the star. Besides using a coronagraph to to be nearly co-planar. HR 8799 has the look and feel of reduce the star’s light, the team used adaptive optics to a scaled-up solar system, and it’s almost certain that the compensate for the blurring eﬀ ects of Earth’s atmosphere. companions formed inside a disk, as did Earth and our Adopting an observing technique invented by Marois, the planetary neighbors. Preliminary dynamical studies also team took advantage of the ﬁ eld-of-view rotation of the alt- suggest that if the objects had brown dwarf masses, the az mounted telescopes. They took images every 10 to 30 system would be gravitationally unstable, and that the seconds to separate, after processing, the exoplanets’ faint planets are less massive than the values inferred from glows from the star’s scattered light. their luminosities. And as Marois says, “Nobody has ever Based on the bodies’ separations from the star and HR found several brown dwarfs individually orbiting a star. 8799’s measured 130-light-year distance, they orbit at dis- With the evidence we have, I believe this system is truly tances of about 24, 38, and 68 a.u. With the companions’ the ﬁ rst picture of a multiplanet system.” infrared luminosities, and the star’s estimated 60-million- Astronomers have yet to adopt an oﬃ cial line of demar- year age, Marois and his team estimate the masses to be cation to distinguish planets from brown dwarfs. Many around 10, 10, and 7 Jupiters, respectively. These masses astronomers think that the distinction should be based on are rather high for planets. Moreover, the star’s age is not formation. With this reasoning, an object forming from known precisely, and astronomers have not thoroughly a collapsing gas cloud (like a star) is a brown dwarf; an tested the cooling models they use to estimate the masses object forming inside a protoplanetary disk is a planet. In of brown dwarfs and planets from their luminosities. this deﬁ nition, the three HR 8799 objects are almost cer- Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Xxxxxx THE HR 8799 SYSTEM Left: The Gemini North telescope acquired this image of HR 8799 in July 2004 + March 2008. The image revealed b c the two outermost planets, b and b + July 2004 c. Right: This image was taken c in September 2008 by Keck II. It showed b and c, as well as an inner planet, d. Crosses indicate the planet positions in earlier images, a clear sign of orbital motion in a system that is nearly pole-on to our July 2008 + d line of sight. From inner to outer, 0.5 arcsec the planets take about 100, 190, 20 a.u. and 460 years to orbit the star. tainly planets despite their high masses. faint objects is a true planet. Instead, these planets might have But other astronomers insist that mass One of the weaknesses of the formation coalesced via a mechanism championed should be the distinguishing characteris- argument is that it’s not always clear-cut by Alan Boss (Carnegie Institution of tic, with the dividing line between planets how a particular object originated. Both Washington) and others. In this scenario, and brown dwarfs drawn at about 12 or Fomalhaut b and the three HR 8799 protoplanetary disks become unstable 13 Jupiter masses. Calculations show objects orbit so far from their stars that and break into clumps of gas, and these that a ball of gas above this threshold has the traditionally accepted method of giant- clumps can rapidly collapse gravitation- enough gravity to compress its core to planet formation fails miserably. Under ally to form giant planets. But as Boss temperatures and pressures high enough this scenario, solid material in a disk admits, “Even this disk-instability method to ignite the fusion of deuterium (“heavy” gravitationally coalesces into a core of sev- has trouble making planets out at 100 hydrogen, with each atom consisting of a eral Earth masses, which has the gravita- a.u., which makes me wonder about the proton and a neutron). Given that Fom- tional oomph to rein in surrounding gas. Fomalhaut planet.” Perhaps Fomalhaut b alhaut b falls well below this line, it’s a But at large distances from a star, orbital formed closer to the star and was scattered planet. In other words, no matter which timescales are too slow for this method to outward during a close encounter with a deﬁ nition one adopts, at least one of these form giant planets. heavier inner planet. Eight days after the Fomalhaut and HR 8799 announcements, the European BETA PIC PLANET Southern Observatory chimed in. A team This composite near- infrared image shows led by Anne-Marie Lagrange (Grenoble the large debris disk Observatory, France) announced a Very around Beta Pictoris. Large Telescope image of a possible planet The Very Large orbiting the young star Beta Pictoris at a Telescope acquired projected distance of only 8 a.u., putting it images of the inner comfortably within the realm of the giant part of the disk, planets in our solar system. Cooling mod- revealing a smudge els suggest a mass of about 8 Jupiters. near the blocked- Unlike the other discoverers, however, out central star. The Lagrange’s group has not yet established object might be a either a common proper motion of the planet with the mass of about 8 Jupiters, companion, or orbital motion, and the team ESO / ANNE-MARIE LAGRANGE AND OTHERS explain several features in Beta Pic’s dust but it could also be a readily concedes that the discovery awaits background star. conﬁ rmation. But as Lagrange says, the planet has the right mass and separation to disk, including an inclined inner disk. All three host stars are relatively young, have masses about twice that of the Sun, 24 March 2009 sky & telescope and belong to spectral type A. Recent Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Wishlist For My ground-based radial-velocity studies of the back-and-forth wobble of A stars show that To listen to podcast interviews Next CCD Camera they tend to have more massive planets with exoplanet discoverers Paul than stars like the Sun, and their planets Kalas and Christian Marois, visit SkyandTelescope.com/skytel. Anti-Ghosting Technology tend to be farther out. This is not surpris- ing, given that A stars form inside larger and more massive disks of gas and dust, direct images represent a huge leap Fastest Download Speeds which means there is more material avail- forward in exoplanet studies, and more able to make planets. pictures are sure to follow. “We may be Finest Frame Quality In addition, Fomalhaut b and the witnessing the birth of a new exoplanet outermost planet around HR 8799 lie just era. For the ﬁ rst time, we may measure Superior CCD Cooling inside a dusty debris disk, the residue orbits, brightnesses, and spectra of other of asteroids and comets colliding and planets, just as astronomers have done for 16bit Data @ All Speeds grinding themselves down to dust (S&T: decades with stars, nebulae, and galaxies,” November 2008, page 32). The discovery of says veteran exoplanet hunter Geoﬀ Marcy Lowest Noise Available two planets just inside a debris disk gives (University of California, Berkeley). astronomers a golden opportunity to study The systems reinforce the growing Reliable Shutters the interaction of planets and disks. If the realization that planetary systems come in Beta Pic planet holds up, it too will provide a staggering variety of architectures. As No Epoxy Seals!!! excellent fodder for dynamical studies. exoplanet researcher Greg Laughlin (Uni- ated d d d d d d Wi indow W ated d d d d d d Wind Win Win Win n n n n n n n n n n n n n n n n n n n n n n n n n n n n nd Win Window W Win n n n n n n n n n n n n n n n n n Interestingly, the unexpected blue color versity of California, Santa Cruz) points AR Coated Windows of Fomalhaut b indicates that it’s embed- out, “With Fomalhaut and HR 8799, we’re ded inside its own miniature dust cloud. probably observing planetary systems that Kalas and his colleagues speculate that the have even less kinship to our own solar planet might be in the process of form- system than do systems that harbor hot ing moons like the four Galilean satellites Jupiters.” ✦ around Jupiter. Regardless of the S&T Editor in Chief Robert Naeye uncertainties in reported on the ﬁ rst exoplanet formation and image claims in the August CALL semantics, these 2005 issue. FLI!!! RBI ANNIHILATOR Residual Bulk Image - A problem with many front illuminated sensors. When cold, a CCD allows trapped photoelectrons to leak over time which creates unwanted ghost images! The RBI Annihilator eliminates RBI as a problem - DAVID LAFRENIERE / PAUL KALAS Finger Lakes Instrumentation Another FLI ﬁrst. FLI (585) 624-3760 PLANET HUNTERS Christian Marois (left) and Paul Kalas (right) led the teams that acquired the ﬁ rst extrasolar-planet images that are likely to stand the test of time. Both photos were taken near www.ﬂicamera.com the summit of Mauna Kea, the volcano on Hawaii’s Big Island that is home to the Keck and Gemini telescopes where the planets were discovered. SkyandTelescope.com March 2009 25 Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

A Bare, Roasted World Messenger’s second flyby of the “iron planet” Mercury Gets a Second j. kelly beatty Look At left is a close-up of the relatively young, 68-mile-wide crater in Mercury’s north that splashed rays far around the globe. The bright spot formed by the rays near it was seen by telescopic observers even before Messenger’s arrival. NASA / JHU-APL / CARNEGIE INST. OF WASHINGTON 26 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

both satisfies and tantalizes. Last October 6th, for the second time in 10 months, NASA’s Messenger spacecraft cruised within 125 miles (200 km) of Mercury’s Sun-baked surface. Pictures and other measurements recorded during the ﬂ yby streamed back to Earth the next day, revealing an incredible land- scape of cratered plains splashed with bright ray craters that will keep the mission’s geologists giddily busy for a long, long time. They’re giddy because the spacecraft revealed a side of Mercury never before seen at close range. “It’s sober- ing, it’s exhilarating, and it’s great fun,” admits principal investigator Sean Solomon (Carnegie Institution of Wash- ington), “to see an expanse of planetary surface bigger than South America” for the ﬁ rst time. Mariner 10 glimpsed less than half of the surface despite three ﬂ ybys in 1974–75, and Messenger itself skimmed past a diﬀ erent side during its ﬁ rst visit in January 2008 (S&T: May 2008, page 24). Meanwhile, two generations of astronomers back on Earth have struggled to glimpse details in this terra incognita. Now the Messenger mission’s science teams have settled down to the task of ﬁ guring out what it all means. Messenger — short for “Mercury Surface, Space Envi- ronment, Geochemistry, and Ranging” — recorded 1,287 images through 11 ﬁ lters during October’s visit, along with a host of other measurements that will help reveal the composition of Mercury’s surface and wispy atmosphere, the state of its magnetic ﬁ eld, and (ﬁ ngers crossed) the structure of its interior. To the eye, the inner planet looks remarkably colorless. “No matter how we combine the images,” notes Solomon, “Mercury comes out pretty gray.” But it’s not completely gray. For example, Mark Robinson (University of Arizona) notes that slightly darker, ever-so-slightly-blue patches, ﬁ rst seen by Mariner 10, appear here and there all over Mercury’s surface. The source of this material seems to Above: The white stripe that cuts diagonally across this image is part of a complex system of rays emanating from a prominent crater hundreds of miles away. Top right: Kuiper, a relatively fresh, 39-mide-wide impact crater, is ground zero for its own splashy network of bright rays that extend hundreds of miles across the surface. NASA / JHU-APL / CARNEGIE INST. OF WASHINGTON (3) Right: Taken last October 6th from a distance of 17,000 miles (27,000 km), this Messenger image of Mercury shows the almost global pattern of bright rays emanating from the fresh crater near the northern limb seen in closeup at left. SkyandTelescope.com March 2009 27 Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

A Bare, Roasted World be deep seated — it’s unearthed by largish impacts, yet only surrounds some of them. Robinson and the mission’s other geochemists will have a much easier time deducing the origin of these mysterious deposits once the spacecraft starts orbit- ing Mercury in 2011. For now, he can only speculate that the blue-tinged stains might contain the mineral NASA / JHU-APL / ARIZONA STATE UNIV. / CARNEGIE INST. OF WASHINGTON ilmenite (iron-titanium oxide) or perhaps small grains of metallic iron. All told, the spacecraft has now scrutinized nearly all of this world (see maps below), and some global proper- ties are becoming apparent. For example, after examin- Smooth, lightly pitted plains cover the ﬂ at ﬂ oor of the walled plain Rudaki (75 miles across, at lower right). A broad region to its west (left) is also smooth. Geologists had used Mariner 10 images to deduce that these are vast volcanic ﬂ ows, which cover more than a third of the planet’s surface. NASA / JHU-APL / CARNEGIE INST. OF WASHINGTON 3 to 3½ billion years ago, or they could turn out to be contemporaneous with the lunar maria, which erupted considerably younger. Churning Core, Vexing Vapors Mariner 10 discovered that Mercury is magnetized, and Messenger’s two ﬂ ybys show that the strength of the planet’s magnetic ﬁ eld is nearly equal on opposite sides of its globe. As Brian Anderson of JHU’s Applied Physics Mercury shows ing the heights and depths measured along a 1,000-mile Laboratory explains, this matchup means that the planet’s no color to (1,600-km) swath of terrain, investigator Maria Zuber ﬁ eld is strongly dipolar (like Earth’s), very nearly centered the eye. But (MIT) concludes that the just-seen hemisphere is about on its massive iron core, and aligned within 2° of the rota- when images 30% smoother than the one seen last January. Planetary tion axis. All this suggests that Mercury generates its ﬁ eld taken through scientists have seen these two-faced appearances else- by a churning motion within a partially liquid outer core, Messenger’s 11 where — on the Moon, Mars, and Iapetus, for example. conﬁ rming a conclusion reached last year by a combination color ﬁ lters are In Mercury’s case, the dichotomy might reﬂ ect cratering of ground-based radar work and theoretical deduction. combined and diﬀ erences (rougher implies older terrain), or it might be The barely-there wisps of vapor surrounding Mercury enhanced, dif- a manifestation of goings-on in the planet’s interior. are technically an exosphere — atoms not permanently ferent hues are As more of the images get scrutinized, it’s becoming bound by gravity but rather escaping into space. What’s revealed. Above, some ancient clear that volcanism has shaped much of the planet’s got the science team scratching its collective head is that terrain is seen surface geology. Widespread patches of smooth terrain, Messenger has detected emissions from sodium, calcium, to be slightly dubbed “intercrater plains” after being spotted by Mariner magnesium, and hydrogen atoms in amounts that dif- blue. Intruding 10, bear the hallmarks of ancient lava ﬂ ows. Geologists fered between the ﬂ ybys. These atoms must be coming younger plains are struggling to determine the age of these outpourings, from somewhere on the surface, but the how, where, and are redder. which blanket up to 40% of the surface. They might be why of their origin remain unknown. NASA / JHU-APL / CARNEGIE INST. OF WASHINGTON As incredible as these results are, keep reminding yourself: “Messenger really hasn’t gotten to Mercury yet.” Sure, it’s had two eye-popping ﬂ ybys, and there’s a third next September 29th. But the instrument-laden craft won’t really get down to business until it starts orbiting the “iron planet” on March 18, 2011. ✦ Left: Mariner 10 recorded only 45% of Mercury’s surface during its ﬂ ybys in 1974– Senior contributing editor J. Kelly Beatty will spy on the 75, as shown on this Mercator map of the globe. Right: Thanks to Messenger’s two innermost planet in late April, when it’ll be particularly well ﬂ ybys so far, more than 90% of the planet has now been seen at close range. placed for evening viewing. 28 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Sun-Earth Connection K R I S TI NA G R I FANTI N I SOLARIMPACT Hed.article Deck Variations in the Sun’s output inf luence Earth’s climate in ways scientists are still trying to discern. 30 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C Copyright 2009, New Track Media, LLC. All Rights Reserved. 1/23/09 1:40:20 PM SUN Layout Mar NEW.indd 30 1/23/09 1:40:20 PM SUN Layout Mar NEW.indd 30

From Earth, the Sun appears as a smooth, glow- the ﬂ ow of energy from deeper down, they are a few thou- ing disk, its intense shine warming our planet. But if we sand degrees cooler than the rest of the photosphere, and could ﬂ oat just above that scorching orb, we would see a thus appear darker than their surroundings. seething cauldron of gigantic bubbles. In the churning Although sunspots are places of reduced temperature, sea of 10,000ºF (5,500ºC) gas, dark eddies materialize, their presence ironically signals a more energetic Sun. lasting for hours to months, and appear to slowly rotate During solar maximum, bright active regions called across the Sun. faculae (Italian for “little torches”) and nearby plage areas Through ﬁ ltered telescopes and sometimes without also increase in numbers. The enhanced energy output magniﬁ cation, these sunspots look like splatters of ink from these bright regions is twice as large as the reduced against the pale disk. More than just a cosmetic distur- energy from sunspots, resulting in an overall brightness bance, the waxing and waning of the spots signal that the increase during solar maximum. Sun’s chaotic moods may inﬂ uence Earth’s climate. Satellites have shown that the Sun brightens in visible light during solar maximum by approximately 0.1% and Fire in the Sky radiates considerably more energy in ultraviolet light and While searching for the imaginary planet Vulcan in the X rays, which are absorbed in Earth’s upper atmosphere. mid-1800s, German astronomer Heinrich Schwabe linked The active regions responsible for these changes also give sunspots to a cycle that rises and falls. These cycles aver- rise to magnetic eruptions that produce ﬂ ares and coronal age about 11 years, and each has a sunspot maximum mass ejections higher in the solar atmosphere. and minimum. Only a handful of small sunspots appear during the low point, while dozens of larger ones arise The Little Ice Age in groups during solar maximum. Half a century later, In 2003 Gerald North (Texas A&M University) showed George Ellery Hale used a spectroheliograph to correctly that Earth’s surface temperatures vary in a way that corre- infer that sunspots have strong magnetic ﬁ elds, linking lates to the 11-year sunspot cycle, but only by about 0.1ºC. the 11-year sunspot cycle to a magnetic cycle. Mathematician Ka-Kit Tung (University of Washington) In the past 30 years, satellites have examined the Sun’s later found a change of about 0.2ºC. “At the 11-year time magnetic cycle in greater depth. The European-NASA scale there is a detectable signal, but it’s very tiny. It Solar and Heliospheric Observatory (SOHO) has made doesn’t have any consequences for humans,” says North. exquisitely detailed measurements for a full 11-year cycle, Though the eﬀ ect of this diﬀ erence on climate appears while the Japanese-American spacecraft Hinode has to be modest, scientists point to a puzzling time in taken some of the highest-resolution images of the Sun Earth’s history when several unusually low sunspot cycles since its launch in September 2006. occurred in succession. During the 1614 solar peak there The Sun’s magnetic ﬁ eld, which pervades the entire were well over 100 sunspots. But from 1645 to 1715 there solar system, arises from a dynamo process operating in was a sustained period when sunspots were nearly absent. the interior. A number of motions maintain the dynamo, This period is named the Maunder Minimum after Eng- including the Sun’s rotation and the ﬂ ow of material from lish astronomer Edward Maunder, who ﬁ rst noted this the equator to the poles. These motions cause bubbles trend retrospectively in 1893. It was closely followed by the of hot, electrically charged gas (plasma) to rise up to the Dalton Minimum, which lasted from about 1795 to 1825. Sun’s visible surface (the photo- Around this time, extremely cold spells were so The 1-meter Swed- sphere) and expand into the corona, pronounced, especially in Northern Europe, that some ish Solar Telescope captured this sunspot producing localized magnetic ﬁ elds researchers have dubbed the period from roughly 1450 to group in 2002, near that alter a region’s temperature. 1850 “the Little Ice Age.” The Maunder Minimum coin- solar maximum. The These processes modify the Sun’s cided with the coldest part of the Little Ice Age — when in largest sunspot is energy output. Although scientists many regions of Europe glaciers expanded, warm sum- nearly 20% larger than accept the dynamo as the driving mers disappeared, and rivers, harbors, and canals froze. Earth. The intense force of the Sun’s magnetic cycles, Climate models based on temperature reconstructions magnetic activity of modeling its intricate workings is suggest a global cooling of about 0.2ºC, and as much as a sunspots blocks heat ﬁ endishly complex. full degree or more in certain parts of Europe. rising from the interior, Magnetic-ﬁ eld lines often A scarcity of sunspots indicates a sluggishly inactive leading to a tempera- coalesce and tangle, suppressing Sun, of which the Maunder and Dalton minimums are ture 2,300 to 3,200°F the upward ﬂ ow of energy, creating just the most recent examples. Since sunspots have been (1,300 to 1,800°C) cooler than the sur- sunspots. Because sunspots block recorded only since around 1610, scientists have looked rounding gas. SkyandTelescope.com March 2009 31 ROYAL SWEDISH ACADEMY OF SCIENCES C Copyright 2009, New Track Media, LLC. All Rights Reserved. Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. 1/23/09 1:40:24 PM SUN Layout Mar NEW.indd 31 SUN Layout Mar NEW.indd 31 1/23/09 1:40:24 PM

Sun-Earth Connection This color-enhanced image from the Preci- sion Solar Photometric Telescope, taken in 2001 near solar maximum, shows the bright light from faculae beating out the darkening from sunspots. The graph at the upper right shows that the Sun is generally slightly brighter at times of high sunspot activity. Although Earth receives slightly more solar energy at solar maxi- mum, it’s not enough to have any noticeable eﬀ ect on climate. NASA / GSFC SCI VISUALIZATION STUDIO / SOURCE DATA: HAO & NSO PSPT at other indirect measurements to try to understand how Judith Lean (U.S. Naval Research Laboratory). Perhaps solar activity has changed during past millennia. the prevalence of these isotopes is not just inﬂ uenced When the Sun is magnetically active, the solar wind by solar activity, but also by climate, so the record is not is stronger and deﬂ ects the high-energy galactic cosmic straightforward. Local weather can also cause variations. rays that constantly bombard Earth. Conversely, when “There is no clear physical process that can be invoked solar activity is less energetic, more cosmic rays strike to explain a strong global cooling as a result of the Maun- our atmosphere and create isotopes such as carbon-14 and der Minimum,” adds climate modeler Chris E. Forest beryllium-10. These isotopes eventually end up in tree (MIT). But he cites enhanced volcanic activity as a possible rings and ice cores, respectively. Studies showing that reason. Europe’s and North America’s “Year Without a more carbon-14 accumulated in tree rings led to the dis- Summer” in 1816 corresponded to the 1815 catastrophic covery of the Spörer Minimum, from about 1450 to 1550, volcanic eruption of Tambora in Indonesia, which spewed which marks the onset of the Little Ice Age. hundreds of megatons of heat-reﬂ ecting dust, rock, and “The beryllium and carbon records are a little ambigu- aerosols into the atmosphere. It also occurred in the midst ous in these minima,” says solar-terrestrial physicist of the Dalton Minimum. “The Little Ice Age can be explained in the models through a combination of the fairly intense volcanic activ- ity and the relatively low solar output,” says climatolo- gist Michael Mann (Penn State University). “When you decrease solar output by the amount we think took place during the Maunder Minimum, the models predict that has enough inﬂ uence on the North Atlantic jet stream to cool parts of Europe a couple of degrees Celsius, even though that same change in solar output cooled global temperatures by only a tenth as much.” “The solar inﬂ uences on Earth’s climate over the last several decades have been very small,” adds Thomas Karl, director of the National Oceanic and Atmospheric Admin- istration’s National Climatic Data Center. But he aﬃ rms that solar cycles are potentially extremely important, as evidenced by the Little Ice Age, when sunspots disappeared. “The data have a lot of interpretation, but nevertheless These images from the National Solar Observatory’s Vacuum Tower Telescope show solar activity falling and rising from 1992 to 2001. there’s some pretty good evidence to suggest there was less solar irradiance, and it did inﬂ uence weather.” LOCKHEED MARTIN SOLAR & ASTROPHYSICS LABORATORY / NATIONAL SOLAR OBSERVATORY / AURA / NSF 32 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. Copyright 2009, New Track Media, LLC. All Rights Reserved. C 1/23/09 1:40:25 PM SUN Layout Mar NEW.indd 32 1/23/09 1:40:25 PM SUN Layout Mar NEW.indd 32

Facular Change in watts per square meter –2 4 2 0 Brightening Watts per square meter 1364 Total Solar Irradiance 1362 1360 1358 Sunspot –4 1980 1985 1990 Darkening 2000 2005 1356 1980 1985 1990 1995 2000 2005 1995 Year Year Not all solar cycles are created equal. Periods with minimal Sunspots Sunspot number 100 Minimum 150 sunspot activity have coincided with cool spells on Earth. Dalton 50 0 Maunder Minimum 1650 1700 1750 1800 1850 1900 1950 2000 Year JUDITH LEAN / U.S. NAVAL RESEARCH LABORATORY (3) But for the major ice ages, climate models show that irradiance — the total energy from the Sun across dif- the orbital mechanics of Earth’s revolution around the ferent wavelengths — have mainly come from the Solar Sun and changes in Earth’s axial tilt were responsible for Maximum Mission, the Upper Atmosphere Research the major wax and wane of the glacial advances. Satellite (UARS), Nimbus 7, the Earth Radiation Budget Satellite (ERBS), ACRIMSAT, and particularly the current Solar Activity and Today’s Climate Solar Radiation and Climate Experiment (SORCE) mis- Research on extreme past climate conditions also raises sion, which carries state-of-the-art solar radiometers that the question of whether solar variations play any role in monitor both the total energy and spectrum. recently observed global climate changes. The large major- “Since the late 1970s, the global temperature increase ity of climate scientists agree that anthropogenic activities has been pretty constant,” says Karl, by almost 0.2ºC per have a greater eﬀ ect on these shifts than do variations in decade, as measured by a land and sea monitors. “Since solar activity. But climatologists don’t completely under- then we’ve seen very little overall change in the energy stand the ways in which solar variation aﬀ ects Earth, so from the Sun based on direct satellite measurements.” they have diﬃ culty reaching a consensus on how much Because these satellites provide absolute measurements, solar variations contribute to climate changes. their results must be compared to one another, which Although reconstructions of solar brightness based leaves room for interpretation. “Irradiance is a diﬃ cult on sunspots and isotope records point to a slight increase measurement because it’s absolute,” says Lean. “You rely in solar output since the beginning of the 1900s, most on the radiometers being stable and you have to cross-cali- experts say that trend has tapered oﬀ after about 1950. brate.” Researchers hope to acquire a long-term record of Aside from SOHO, measurements of the Sun’s total solar irradiance from SORCE and its follow-on missions, Glory and NPOESS, which will carry Volcanoes can profoundly solar radiometers. “We need to inﬂ uence Earth’s climate. know how irradiance changes This Landsat image shows from cycle to cycle and if long- Tambora, on the Indone- term trends are really occur- sian island of Sumbawa. ring,” says Lean. “Without the In April 1815 Tambora long-term data, it’s impossible unleashed the most power- to validate the historical recon- ful volcanic eruption of the past millennium, killing structions of solar brightness more than 70,000 regional changes that climate research- inhabitants and contribut- ers currently use.” 5 miles ing to 1816’s “Year Without Climate models do take into USGS a Summer.” account the slight increase of SkyandTelescope.com March 2009 33 Copyright 2009, New Track Media, LLC. All Rights Reserved. C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. 1/23/09 1:40:45 PM SUN Layout Mar NEW.indd 33 1/23/09 1:40:45 PM SUN Layout Mar NEW.indd 33

Sun-Earth Connection Top and bottom left: The eﬀ ects of global climate change are easily seen in glaciers such as McCall Glacier in Alaska’s Brooks Range. Many glaciers are receding extremely rapidly on a geologic timescale as polar regions become warmer. Center left: The graphs compare various factors and their associated temperature changes (orange lines) that inﬂ uence Earth’s climate: El Niño, volcanic aerosols, solar irradiance, and human activities. The inset in the bottom graph shows how greenhouse gases, tropospheric aerosols, and changes to surface reﬂ ectivity combine to yield the net human factor. In the bottom main graph, the orange line’s recent steep upward slope shows that human activities, mainly green- 1953 house-gas emissions, play the dominant role in the overall global warming measured in recent years. Natural processes play too small a role to account for most of that trend. Surface Temperature Variability Components 3 0.2 solar output in the early 20th century. “Models indicate that El Niño 2 0.1 1 solar forcing can explain about 0.1 to 0.2ºC of the warm- 0.0 0 Index ing in that early period. Since the net trend is close to 1ºC, –1 –0.1 solar output increase can probably only explain about 20% –2 of 20th-century warming,” says Mann. “If you don’t put 0.0 0.00 human impact in the models, and you just include solar 0.05 and volcanic activity, you can’t explain the 20th-century –0.1 Volcanic aerosols Optical depth warming; you get a slight cooling.” –0.2 0.10 0.15 Taking Earth’s reﬂ ectivity and geometry into account, –0.3 recent solar cycles have produced a variation of about 0.2 0.2 1368 watt per square meter at the surface. In addition to this Solar irradiance 0.1 1367 direct surface heating, the more advanced climate models 0.0 1366 Total w/m 2 factor in solar-cycle ultraviolet eﬀ ects in the atmosphere. –0.1 1365 But human greenhouse-gas emissions have led to the –0.2 1364 equivalent of about a 2.5-watts-per-square-meter increase 0.8 3 since preindustrial times, which is only partially oﬀ set by 0.6 2 1 Greenhouse gases Anthropogenic inﬂuence 1.5 an approximately 1-watt-per-square meter cooling from 0.4 (w/m 2 ) 0 Land + snow 1.0 industrial aerosols injected into the troposphere. As a –1 Aerosols result, most models suggest that the past century’s pro- 0.2 Change in watts per square meter (w/m 2 ) 1900 1920 1940 1960 1980 2000 0.5 TOP PHOTO: AUSTIN S. POST / GRAPH SOURCE: JUDITH LEAN / BOTTOM PHOTO: MATT NOLAN (UNIVERSITY OF ALASKA, FAIRBANKS) / BOTH PHOTOS COURTESY NATIONAL SNOW AND ICE DATA CENTER nounced warming is mainly caused by human factors. 0.0 A more controversial hypothesis on how solar activity –0.2 0.0 inﬂ uences Earth’s climate points to the solar wind. Physi- –0.4 cist Henrik Svensmark (Danish National Space Institute) 1900 1920 1940 1960 1980 2000 and others suggest that the increased ionization in the troposphere from cosmic rays may aﬀ ect cloud coverage. The ionization may stimulate the formation of clouds, which reﬂ ect heat back into space. The group speculates that when solar activity is weaker, more cosmic rays hit Earth and cloud formation builds up, decreasing the heat that reaches Earth’s surface. The group compared data from satellites and cosmic- ray monitors. “We found a correlation of cosmic rays with low clouds within the ﬁ rst couple of kilometers of the troposphere,” says Eigil Friis-Christensen, director of Denmark’s National Space Institute, where the team is testing Svensmark’s hypothesis. By building an artiﬁ cial 2003 cloud chamber, the researchers found evidence that ion- C Copyright 2009, New Track Media, LLC. All Rights Reserved. Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. 1/23/09 1:40:48 PM SUN Layout Mar NEW.indd 34 SUN Layout Mar NEW.indd 34 1/23/09 1:40:48 PM

THE NEXT MAUNDER MINIMUM? When might the Sun enter another Maunder Minimum? Mark Giampapa (National Solar Observatory) and his colleagues have studied the magnetic behavior of stars in the open cluster M67 that are similar to the Sun in mass, composition, and age. This program suggests that Sun-like stars spend about 17% of the time in a very-low-activity phase. Studies of tree rings and ice cores yield similar results. Since the Sun spent about 70 years in the Maunder Minimum, and that was 300 years ago, these studies suggest we might have to wait a century or longer for another low-activity phase. SOHO / ESA / NASA ization by cosmic rays leads to an increased formation of indicator, but really we have to understand the other things ultra-ﬁ ne aerosol particles, which are the basis for the for- that are related, like the bright faculae,” says Lean. “Solar mation of cloud condensation nuclei in the atmosphere. activity can change, but it’s the proportion of sunspots and The team is currently testing its hypothesis by trying to faculae that determine how the irradiance changes.” Once stimulate the formation of ultra-ﬁ ne aerosols in an aban- scientists understand how irradiance varies from cycle to doned coal mine, where no cosmic rays can reach. cycle, they will be able to better understand if To listen to a podcast with solar-terrestrial Looking Ahead there are longer-term physicist Judith Lean, visit SkyandTelescope .com/skytel. While each solar cycle has a sunspot minimum and maxi- trends as well. mum, no one knows why the Sun and other middle-aged solar-type stars have this ebb and ﬂ ow, ranging from 8 to The Next Cycle 15 years. Astronomers are currently noticing a delayed start to In early 2010 NASA plans to launch the Solar Dynamics Cycle 24. Cycle 23 has lasted for a full 12 years, longer Observatory (SDO). Equipped to peer beneath the Sun’s that the two prior cycles, but similar to Cycle 20. Until surface, image sunspots, and measure the Sun’s magnetic November 2008, professionals and amateurs went months ﬁ eld, SDO is the ﬁ rst mission in NASA’s Living with a Star without a single sunspot sighting. While it’s presently far program to better understand solar variability. SDO will too early to liken this delay to the Maunder Minimum, image the Sun’s corona at a range of temperatures in the a recent study by National Solar Observatory scientists extreme ultraviolet six times a minute for ﬁ ve years. suggests that sunspots may be growing cooler and less “This is the next big thing — it will bring more data magnetic since 1990, and they hypothesize that sunspots by a factor of a thousand,” says Karel Schrijver (Lockheed may soon disappear. Martin Solar and Astrophysics Laboratory), who helped These results are potentially exciting, says Yi-Ming develop SDO. Although SDO will not measure solar irradi- Wang (U.S. Naval Research Laboratory), but he cautions ance, it will record the Sun’s extreme ultraviolet and X-ray that we are still in the low part of Cycle 23 and more mea- emission, which heats Earth’s upper atmosphere. surements are needed during the next solar maximum to Scientists have only fully measured the total solar irra- distinguish a long-term trend from a solar-cycle variation. diance in the last two solar cycles. Interestingly, “irradi- Predictions vary about what will happen in the upcom- ance changes in [the just-ending] Cycle 23 were about the ing cycle, which should peak around 2012. Some solar same as Cycle 22, even though the sunspot numbers were physicists are forecasting the upcoming cycle to be one diﬀ erent,” says Lean. of the highest on record, while others claim it will be Related faculae are also a source of irradiance variation, unusually low. Reﬁ ning our understanding of the solar and sunspots by themselves are incomplete indicators of cycle and studying the Sun in closer detail may eventually the solar cycle. To ﬁ gure out how the Maunder Minimum aid in determining — and perhaps anticipating — what inﬂ uenced climate, scientists would need to know what consequences the shifting Sun has on Earth. ✦ was happening with faculae, but such records don’t exist. “The key is understanding the solar-activity cycle, which Former S&T editorial intern Kristina Grifantini is a science produces magnetic ﬁ elds. Sunspots we use as a generic and technology writer based in Cambridge, Massachusetts. SkyandTelescope.com March 2009 35 Copyright 2009, New Track Media, LLC. All Rights Reserved. C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. 1/23/09 1:40:56 PM SUN Layout Mar NEW.indd 35 SUN Layout Mar NEW.indd 35 1/23/09 1:40:56 PM

S & T Test Report Alan Dyer Short and Sweet Does TMB’s new 92-mm refractor live up to the claim that it’s a replacement for the legendary Astro-Physics Stowaway? TMB-92 Signature Series Refractor Supplied with dual-speed 3-inch Feather Touch focuser, 1¼-inch adapter, dew shield, dust covers, and hard carrying case (optional 114-mm tube rings are available for $99.95). US Price: $1,999.00 TMB Optical tmboptical.com Sold by select dealers, including Astronomics (astronomics .com) and High Point Scientiﬁ c (highpointscientiﬁ c.com) Even with its dewcap fully extended, the TMB-92 still boasts a very compact tube assembly. With the dewcap collapsed, the telescope can be stored in its included hard-sided carrying case with the tube rings in place, a nice convenience. ALL PHOTOGRAPHS TAKEN BY AUTHOR 36 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

When I opened its ﬁ tted carrying case for my ﬁ rst look at the TMB-92 refractor, I thought, “Wow! Is it ever short!” And no wonder. Part of TMB’s Signature Series, this 92-mm apochromat is a fast f/5.5 triplet-lens design, making for a stubby, ultra-compact tube assembly. The little apo is said to “ﬁ ll the void left by the discontin- ued 90mm Astro-Physics Stowaway,” a scope so revered The author star-tested the TMB-92 (left) against his limited-edi- by observers that it became a legend in its own time. tion Astro-Physics 92-mm f/7 Stowaway (right), an instrument that has become the gold standard for small apo refractors. I tested the TMB-92 against a Stowaway, albeit not an original f/5 model but a later, longer-focal length f/7 Stow- away. The new TMB fared very well indeed when pitted against this remarkable Astro-Physics apo. The TMB-92 presented images of bright stars and planets that were as free of chromatic aberration (false color) as the Stowaway. It’s fair to say that the TMB had no visible chromatic aber- ration, stunning for such a fast instrument. In other star tests, however, the Stowaway pulled ahead. While it had no astigmatism, the TMB did exhibit slight spherical aberration WHAT WE LIKE: from an undercorrected lens, even on cool autumn First-class color correction nights. Star images viewed Superb focuser and ﬁ ttings at high magniﬁ cations Compact tube, adaptable were not quite identi- for binoviewers cal inside and outside of WHAT WE DON’T LIKE: focus. And in focus, stars exhibited diﬀ raction rings Slight spherical aberration that were a touch brighter Heavy for its aperture class than expected for an ideal Photography requires third- image. Jupiter looked just party ﬁ eld ﬂ attener a bit soft — though only when compared to the Stowaway in side-by-side testing. If I were to rate the Stowaway with 5 stars for opti- cal perfection, then the TMB-92 earns 4½. Considering that Stowaways have been known to command $5,000 to $6,000 on the used market, $2,000 for a new TMB-92 is an excellent bargain. Adding to its value, the TMB handily beat the Stow- away when comparing their tube assemblies. The TMB has a robust, 3-inch-diameter Feather Touch focuser (model #3025), which can be rotated for best camera and eyepiece orientations. The TMB’s drawtube locks securely for use with cameras and heavy eyepieces. But there is a price to pay for this heavy-duty focuser. The TMB’s large- diameter tube assembly weighs in at more than 9 pounds, The North America Nebula captured with a 48-minute exposure at ISO 400 and the TMB-92 setup as shown on page 39. SkyandTelescope.com March 2009 37 C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

S&T Test Report SPECIFICATIONS & MEASUREMENTS* TMB-92 Signature Series Refractor Clear aperture 92 mm Eﬀ ective focal length 505 mm Focal ratio f/5.5 Weight 9.4 pounds (4.3 kg) Minimum tube length (assembled) 15 inches (38 cm) * All measurements by Sky & Telescope. For those who want to use the TMB-92 with a binoviewer, the scope features a removable tube section, which locks solidly into place with over-sized, nylon-tipped, thumb- With the tube section in place for screws. The focuser’s drawtube is marked in two loca- normal viewing, and using a conventional tions with an engraved millimeter scale. 2-inch star diagonal, the focuser provided suﬃ cient travel for all of the eyepieces I about 3 pounds more than the trim and I tested a Williams Optics binoviewer tried — from Tele Vue’s 31-mm Nagler slim Stowaway, and as much as some of (similar to other low-cost units), and it and high-power Radians to several models today’s 100-mm refractors. reached focus without its Barlow lens, from the Pentax line. The only caveat But just 15 inches (38 cm) long with but only when inserted into a 1¼-inch involved Tele Vue’s new 8-mm Ethos. This the dewcap retracted, the TMB tube is as star diagonal. When used with a 2-inch eyepiece ﬁ ts both 1¼- and 2-inch focusers, short as some 80-mm apo refractors. And diagonal, the William Optics just reached but it reached focus on the TMB-92 only that’s not all. You can make the scope even focus with the Feather Touch racked all the when used in the 2-inch diagonal with a shorter by removing a 2¼-inch-long tube way in; there was no focus travel to spare. A 1¼-inch adapter, which holds the eyepiece section that connects the focuser to the premium Baader binoviewer, again with no farther out from the diagonal then when main tube. Removing this piece adds the compensating lens in place, focused with it’s inserted directly into the 2-inch holder. several inches of extra “focus travel” that oodles of travel left, thanks to the Baader’s The beauty of the compact TMB scope binoviewers demand. As such, you can special low-proﬁ le 2-inch prism diagonal. is its adaptability for both visual use at enjoy two-eyed panoramic views through Combined with a pair of Tele Vue 24-mm all magniﬁ cations with and without a the TMB at low powers, without the need Panoptic eyepieces, the 3°-wide views binoviewer and for astrophotography. I for a Barlow lens in the system to make of Milky Way starﬁ elds through either used it extensively to take deep-sky images the binoviewer reach focus. binoviewer were spectacular. with a DSLR camera, a task well suited to Quick Look Meade’s LightSwitch Technology Debuting in an ad in last month’s issue and at the Las Vegas International Con- sumer Electronics Show in January, the ETX-LS is the latest evolution in Go To telescopes from Meade. Its forte, dubbed LightSwitch technology, is a melding of fully automated telescope setup and the rich multimedia presentations developed for the company’s handheld MySky Plus. Meade calls the $1,299 ETX-LS its most technologically advanced instrument ever. Last November, I had a hands-on preview of the alpha-model ETX-LS pictured here. S&T: DENNIS DICICCO production unit, but the software wasn’t yet Optically and mechanically it was nearly a ready for beta testing. The 6-inch f/10 scope is a new aperture in Meade’s catadioptric 38 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

its fast f/5.5 optics. As with most triplet apos, however, the scope’s inherent ﬁ eld curvature meant star images were sharply focused across only a central 15-mm- diameter image circle. TMB does not oﬀ er a ﬁ eld ﬂ attener for its 92-mm model. But I ran some tests using a Borg 0.85× focal reducer/ﬁ eld ﬂ attener, and stars were recorded as nearly pinpoints out to the corners of an APS-format chip (measur- ing 23 by 15 mm). Similar ﬁ eld ﬂ atteners are available from Tele Vue and Williams Optics, and I would consider one essential for serious imaging with the TMB-92. In all, I’m impressed with this new telescope from TMB. It combines superb optics with solid, well-crafted mechanics for a versatile, compact instrument. What The TMB-92 ﬁ tted with a Borg 0.85× ﬁ eld ﬂ at- more could an apo-lover want? tener and camera adapter, an Orion Autoguider on a 50-mm ﬁ nder/guidescope, and an Astro- Alan Dyer is coauthor with Terence Dickin- Physics Mach 1 mount served as the astropho- son of The Backyard Astronomer’s Guide, tography platform that the author used for his recently published in a revised third edition. Canon 20Da DSLR camera. S&T RATINGS ✭ ✭ ✭ ✭ ✭ Sensibly perfect. No meaningful improvements possible ✭ ✭ ✭ ✭ Any shortcomings will go unnoticed in normal use. Optics ✭ ✭ ✭ ✭ ✭ ✭ ✭ ✭ Problems noticeable but do not seriously aﬀ ect performance. ✭ ✭ Problems noticeable during normal use — performance compromised. Mechanics ✭ ✭ ✭ ✭ ✭ ✭ Problems so severe that the equipment is virtually unusable. Ratings are intended to convey performance compared with equivalent equipment and Overall ✭ ✭ ✭ ✭ ✭ should not be used to predict the relative performance of instruments having markedly dif- ferent designs or speciﬁ cations. line and the smallest yet to feature its The integrated CCD camera also does Advanced Coma-Free (ACF) optics. medium-ﬁ eld astrophotography. And Especially noteworthy is a 640-by-480- the scope’s electronics are plug-and-play pixel CCD camera integrated into the ready for Meade’s line of DSI cameras, telescope tube. With an 8° ﬁ eld of view, it eliminating the need for a separate com- automatically identiﬁ es stars during the puter in the ﬁ eld. Images can be viewed scope’s initialization process, thus pro- on any video monitor connected to the viding hassle-free (maybe even foolproof) scope’s video output and stored on an SD Go To alignment. The mount’s large memory card for transfer to a computer. metal gears and robust DC servo motors You’ll need a user-supplied video should deliver Go To pointing and track- monitor to fully experience the ETX-LS’s ing performance that’s more in line with multimedia content. Even without one, the company’s high-end telescopes than the built-in speaker lets you listen to the it is with previous Go To models in the audio commentary on hundreds of celes- ETX family. While Meade is mum on tial sights. This material adds a new level whether larger LightSwitch scopes are of excitement to a “ﬁ rst” telescope or one in the works, it’s clear to me that the that’s used for public outreach. current mount will easily support the We’ll schedule a full Test Report on company’s 8-inch ACF and maybe even the ETX-LS as soon as production units its 10-inch. become available. ✦ — Dennis di Cicco Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

New Product Showcase ▾ EASY SEATED VIEWING With its EasyView Arm (starting at $149) for alt-azimuth telescope mounts, Universal Astronomics conquers the diﬃ culties that wheelchair-bound observers face when using telescopes. The arm’s innovative double-jointed design allows panning across half of the sky without the observer having to move to the other side of the tripod. Light- and medium-duty EasyView Arm models are available, and both can be easily assembled by users who are physically chal- lenged. The EasyView Arm Light includes 10 pounds (4.5 kg) of coun- terweights and can bear up to 15-pound telescopes, while the EasyView Arm Medium can accommodate scopes weighing up to 30 pounds and comes with 15 pounds of counterweights. Universal Astronomics 6 River Ct., Webster, MA 01570; 508-943-5105; universalastronomics.com CELESTRON ▴ MIDSIZE MOUNT Celestron oﬀ ers a new Go To mount for observers and astrophotographers alike. The CGEM German Equatorial Mount ($1,399) has a load capacity of about 40 pounds. It features steel shafts and gears, brass worm wheels, and low-cog DC servo motors with integrated optical encoders for accurate pointing, slewing, and tracking. The controller includes Celestron’s new All- Star polar alignment routine, which allows you to simply point your scope at any bright star, and the NexStar controller calculates what the target star is, aiding in accurate polar alignment. The CGEM allows user-deﬁ ned slew limits, permanent periodic error correction, and it has an autoguider port that conforms to the ST-4 standard. Also noteworthy is the fact the mount has no external cables run- ning to the motors, reducing the chance of tangles. Visit Celestron’s website for additional details and a list of worldwide dealers. Celestron 2835 Columbia St., Torrance, CA 90503; 310-328-9560; celestron.com UNIVERSAL ASTRONOMICS VIXEN OPTICS ▶ ARMORED BINOCULARS Vixen Optics announces the new Foresta Binocular series. Of particular interest to amateur astronomers is the Foresta 10×50 ZCF model ($279). These lightweight binoculars feature die-cast aluminum bodies encased in a protective rubber coating. The 50-mm, three-element objective lenses and BAK4 prisms are fully multi-coated to minimize light scatter and maximize light transmission. The binoculars are nitrogen-purged to reduce internal fogging, and they are waterproof. A novel hinge- lock allows you to preset your interpupillary distance so that it can be quickly returned to a comfortable position after sharing the views with other observers. The binoculars come with lens caps, neck strap, and a hiking-style carrying case. Vixen Optics 1010 Calle Cordillera, Suite 106, San Clemente, CA 92673; 949-429-6363; vixenoptics.com New Product Showcase is a reader service featuring innovative equipment and software of interest to amateur astronomers. The descriptions are based largely on information sup- plied by the manufacturers or distributors. Sky & Telescope assumes no responsibility for the accuracy of vendors’ statements. For further information contact the manufacturer or distributor. Announcements should be sent to [email protected]. Not all announcements can be listed. 40 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Fred Schaaf Northern Hemisphere’s Sky The Best of March Many of the night sky’s greatest spectacles are on display this month. COUNT LIGHT POLLUTION OUT The Globe at Night star count, now in One of the key goals of the International would appreciate the advice of its fourth year, draws thousands of par- Year of Astronomy (IYA) is to educate people about light readers who visit the website. ticipants worldwide. pollution and energize them to do something about it. Which of my “best sights” This year’s event runs One way is through public star counts (see the box at are shown on our accompa- from March 16th to right). Another is to give people who have always lived nying all-sky map? At least the 28th (see www. near artiﬁ cial lights a chance to experience ﬁ rsthand the one-third of them. globe.gov/GaN). Go out, count some beauty of an unpolluted sky. In any month, the most stars, and invite your Bring people to dark skies. As a member of the splendid sight of all could neighbors too! U.S. IYA’s Dark Skies Working Group, I’m helping to be the entire starry sky on a develop public events at Dark Skies Discovery Sites moonless night — if you can (DSDS). To learn how to have a location that you know get a view of it far from city lights. Even in places that be designated a DSDS, and what DSDS events should be aren’t very dark, ponder the fact that roughly half of the like, go to astronomy2009.us/darkskies. universe is potentially visible above your horizon. One of the activities we recommend for DSDS events A “best sight” that’s easy to view anywhere is Sirius, is using best-sights lists. The idea is to get the public the brightest star in the night sky. At the time of our sky excited about the glories of the heavens — but with an map, Sirius is not far past its highest in the southern emphasis on teaching them that many of these celestial sky. Drink in its glorious sparkling light. wonders are being lost to light pollution. As with star My basic list has only 50 entries, so the only deep-sky counts, which can also be done at DSDS events, the goal objects with individual entries are the Orion Nebula is to get folks personally invested in valuing and saving (M42), the Hyades, the Pleiades (M45), and the Androm- the stars, especially at the local level. eda Galaxy (M31). All of these except M31 are high The best sights in our March sky. As I mentioned enough to view easily on March evenings. last month, my list of the 50 best astronomical sights As mentioned last month, Orion’s Belt and Sword, is now available at SkyandTelescope.com/ﬁ ftybest. I’m Orion itself, and the family of constellations that it looking to make subsets and extensions to the list, and I anchors also merit entries in my list. What other impor- tant and prominent star patterns are must-sees on our March map? Turn the map upside-down so that Facing North is at the bottom and you’ll see another of my list’s joint entries: the Big Dipper and Polaris. The former is now swinging upward in the northeast, and will be even higher at April nightfalls. Venus, Saturn, and the Moon (see page 50) would make anybody’s list of celestial spectacles. But let’s con- clude with one of my generic “best sights” — any large open cluster that can be seen naked-eye. In addition to the Hyades and Pleiades, we have the Alpha Persei Cluster in the northwest, the Beehive (M44) in Cancer AKIRA FUJII high in the southeast, and the great star cluster in Coma Berenices climbing in the east. ✦ The Pleiades and Hyades, now setting in the west, are probably the most spectacular naked-eye star clusters. Fred Schaaf welcomes your comments at [email protected]. 44 March 2009 sky & telescope C Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved.

Charles A. Wood Exploring the Moon Filling Up Copernicus Craters that formed in a similar fashion now look markedly diﬀ erent. On opposite sides of the huge Mare Imbrium lava ﬁ eld are before-and-after versions of a typical impact crater. Just beyond the southern rim of the Imbrium basin is Copernicus, a 58-mile-wide (93-km) crater that’s one of the most magniﬁ cent lunar sights to glimpse through a telescope. And on the northern rim of Imbrium sits 68-mile-wide (109-km) Plato, an equally famous crater that appears quite diﬀ erent. Plato once looked very similar to Copernicus, but has obviously changed immensely. How come? Let’s start with Copernicus, which is a relatively fresh strike (about 1 billion years old) and an excellent example OLIVER PETTENPAUL of a “complex” impact crater. To understand what this means, we must ﬁ rst consider a “simple” crater. Lunar craters smaller than about 10 miles in diameter have low FRESH AS EVER The crater Copernicus is an easy telescopic target near the center of the Moon’s disk, along the southern raised rims and steep inner walls leading to small ﬂ at shore of Mare Imbrium. After the impact of an asteroid some ﬂ oors. The 6-mile-wide Carlini is a good example. Despite 1 billion years ago, the walls slumped, creating the terraced walls its small diameter, Carlini is easy to ﬁ nd in the middle characteristic of a “complex” crater. of Imbrium, just west of a line joining Copernicus and Plato. A telescopic view of Carlini will reveal its bright rim a broad, slightly dark, ﬂ at ﬂ oor about 35 miles in diam- and a shadow bowing across its ﬂ oor. eter. Just south of the ﬂ oor’s center lies a cluster of three Copernicus looks vastly diﬀ erent. Well placed near the central mountains that rise about 3,000 feet (900 meters). center of the Moon’s visible disk, this nearly overhead view These peaks rose when crustal rocks compressed by the makes Copernicus’s true circular shape apparent and impact rebounded. The summits consist of material that provides an excellent view into its interior. Copernicus has originated probably 3 to 6 miles below the surface. The Moon • March 2009 20 N Highlighted feature Size (miles) Description 21 C 10 B A Copernicus (L5) 58 Large complex crater B Carlini 6 Simple crater 22 A C Plato (L83) 68 Large lava-ﬁ lled crater W E L numbers refer to Charles Wood’s Lunar 100 list; see SkyandTelescope.com/lunar100. Mar 8 23 Phases Distances Librations h First quarter Mar. 4, 7:46 UT Perigee Mar. 7, 15 UT Mare Smythii Mar. 8 Full Moon Mar. 11, 2:38 UT 228,053 miles diam. 32′ 33″ Mare Humboldtianum Mar. 10 ANTONÍN RÜKL Last quarter Mar. 18, 17:47 UT h Peary (crater) Mar. 20 S Apogee Mar. 19, 13 UT New Moon Mar. 26, 16:06 UT 251,220 miles diam. 29′ 33″ Volta (crater) Mar. 21 For key dates, black dots on the map indicate what part of the Moon’s limb is tipped the most toward Earth by libration under favorable illumination. SkyandTelescope.com March 2009 55 Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Exploring the Moon PHOTOILLUSTRATION BY JOE REED; SOURCE: OLIVER PETTENPAUL AND GEORGE TARSOUDIS THE BIG FILL If Copernicus had ﬁ lled with lava during the past billion years, the sequence may have looked like this, as Joe Reed, of Midland, Texas, envisioned with the help of image-processing software. His ﬁ nal result has a striking similarity to Plato, shown at the bottom of the page. Another aspect of Copernicus’s com- Like Copernicus, Plato was probably plexity is the circle of serrated walls that about 2½ miles deep with terraced walls rise up about 2½ miles above its ﬂ oor. The and central mountains after it was blasted rim crest has a bright scarp formed when out more than 3 billion years ago. But as parts of the walls slid down as giant ter- the lavas contin- races. Along the eastern side of the wall, I ued to gush out SEEING IMBRIUM count four terraces that step down to the from below, they The largest features on the ﬂ oor. In other places, the walls and nearby piled up higher in Moon are best seen in low- ﬂ oor are covered by more chaotic-looking the crater, gradu- power telescopes or even masses that have slumped. ally burying the binoculars. Try to grasp Imbrium’s overall struc- At ﬁ rst glance, Plato looks nothing like peaks and most of ture before upping the Copernicus. It has a broad ﬂ at ﬂ oor of the wall terraces. magniﬁ cation for a closer mare lava. It’s shallow — only about 1½ Even though look at craters within. That miles deep — and has no visible central Plato is just a way, individual details will peaks and almost no wall terraces. But ﬁ lled-in version retain their context when you view them separately. since all fresh craters with diameters of Copernicus, larger than about 15 miles look like Copernicus will Copernicus, we can safely assume that never become like Plato. The Moon hasn’t Plato originally did, too. The key is the had a substantial volcanic eruption for mare lava on its ﬂ oor. Because the rim of more than 1 billion years — Copernicus Plato is intact, lavas from Mare Imbrium will remain preserved for eons. ✦ couldn’t have ﬂ owed into the crater; they must have risen up through subsurface Charles Wood conducts the Lunar Photo of faults and erupted onto its original ﬂ oor. the Day website at lpod.wikispaces.com. S&T: SEAN WALKER NASA / BROWN UNIV. AFTER THE FLOOD Plato, on the northern edge of Imbrium, can be thought of as a crater similar to Copernicus that suﬀ ered a long period of ﬂ ooding by lava. Left: From Earth, we see Plato at an oblique angle. Right: From orbit, however, as in this image from the Lunar Orbiter 4 spacecraft, Plato’s circularity is readily apparent. Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Tony Flanders Celestial Calendar Venus at Its 8-Year Best Follow the thinning crescent of Venus even as it passes due north of the Sun. Venus puts on a spectacular show for spans nearly a full arcminute from tip to In the days leading up to inferior con- Northern Hemisphere observers in tip in late March — big enough to be seen junction, look for Venus’s cusp extensions February and March. The Evening Star easily in steadily supported binoculars. to appear. These threadlike continuations, continues to glare in the western twilight to The clearest telescopic images of caused by sunlight scattering through the naked eye, but there’s more Venus come when you view the planet Venus’s atmosphere, make the crescent going on than that. In a high in the sky in broad daylight. stretch more than 180°, as shown at left. small telescope Venus is But when doing this, you must be The thinner the crescent becomes, the both enlarging and extremely careful not to aim your more likely you are to detect them. becoming an ever-thinner telescope (or its ﬁ nderscope!) at Once every 8 years — and 2009 is one crescent, with the drama the Sun, or you may end up per- of those — inferior conjunction also pro- culminating as Venus manently blinded. By far the safest vides a special treat for naked-eye observ- plummets toward the sunset JOHN BOUDREAU procedure is to view Venus in mid- to ers. Because Venus passes 8° north of the horizon in mid- to late March. late afternoon, when it’s above the lower- Sun, it should be visible at both dawn and Venus is rounding toward Earth in ing Sun. Place your telescope just inside dusk for at least three days centered on its orbit, so the planet’s apparent size the shadow of a building, so that no part March 23rd at latitude 40° north, as shown swells from 30′ on February 1st to 45′ on of the scope is sunlit. Use binoculars or below. The farther north you live, the lon- March 1st. The telescopic view becomes your ﬁ nderscope to scan above or upper ger the period of dawn-and-dusk visibility genuinely dramatic as Venus approaches right of where the Sun would be if you will be. Find a spot with open horizons to inferior conjunction on March 27th. At that could see it, and you’ll soon locate Venus. the east and west, and scout the sky with point the planet is as close as it will come You can use our Interactive Sky Chart binoculars before attempting a naked-eye to being between us and the Sun. As that (SkyandTelescope.com/skychart) or your sighting. date approaches, the crescent seems too favorite planetarium software to ﬁ nd the thin to be real, and it sports exotic cusp precise distance and angle from the Sun Tony Flanders’s ﬁ rst article as associate edi- extensions as shown above. The crescent to Venus on your date. tor was about Venus’s apparition in 2004. Venus in the Morning Sky 40° 20° March - April 2009 24 29 Feb. 8 13 19 3 10 minutes before sunrise 24 14 18 19 9 23 14 Jan. 9 30° 28 4 Apr. 4 10° Mar. 30 Venus in the Evening Sky 5 25 Venus is shown January - March 2009 10 Mar. much larger than its 20° 20 actual apparent size. 10 minutes after sunset 15 Looking ENE Looking EastLooking East Venus is shown much larger 10° than its actual apparent size. Venus’s appearance changes rapidly in the 20 weeks around inferior conjunction, when it scoots between Earth and the Sun. At its clos- 25 est, Venus is just 0.28 astronomical unit (26 million miles or 42 million km) from Earth. Looking Southwest Looking West-Southwest Looking West 58 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

Celestial Calendar Our Best-Ever Opposition of Ceres When Giuseppe Piazzi discovered the h h 11 10 M ﬁ rst asteroid, 1 Ceres, on January 1, 1801, 11 21 Apr 1 it was magnitude 8.0. This year we’ll see it Mar 1 11 nearly three times that bright, at magni- Path of Ceres 21 21 E tude 6.9, from mid-February through the 11 Z ﬁ rst week of March. This is as close and bright as Ceres will be in our lifetime. Feb 1 Ceres reaches opposition on February D 25th. Using the best orbital elements and G +20° perturbation corrections, S&T’s Roger Sin- nott ﬁ nds that “on February 25th at 23.6 2 hours UT, Ceres will pass closer to Earth 3 [1.583198 a.u.] than it has been since 1857. H 4 Q Ceres won’t be this close again until 4164!” Star magnitudes 5 The reason is that the asteroid is at 6 LEO perihelion, its closest to the Sun, just two 7 weeks earlier. Winter oppositions of Ceres 8 A (winter in the Northern Hemisphere) are when it gets especially close and bright. Regulus I You can spot it with binoculars over the +10° back of Leo using the chart here. A typical The ﬁ rst-discovered asteroid shines at magnitude 6.9 for three weeks around its late-February binocular’s ﬁ eld of view is about 6° wide; opposition. The ticks show its position at 0 Universal Time on the dates indicated. h compare this with the blue ticks 10° apart on the right edge. Ceres will be magni- Ceres is by far the largest asteroid and has a third of the mass in the asteroid belt. tude 7.2 on February 1st, 6.9 on March 1st, enough gravity to pull it into a reason- NASA’s Dawn spacecraft is on its way to 7.4 on April 1st, and 8.0 on May 1st. The ably round shape, making it the smallest take up orbit around Ceres in 2015 after chart shows stars to magnitude 8.0. known “dwarf planet” under the new 2006 dallying at Vesta starting in 2011. With a diameter of 590 miles (950 km), classiﬁ cation. It’s estimated to contain — Alan MacRobert The Hubble Space Telescope resolved markings on Ceres’s round disk in Minima of Algol preparation for Dawn’s arrival there in 2015. The asteroid rotates once every Feb. UT Mar. UT 9 hours. Color contrasts have been 12/30 2003 15:46 UT 12/30 2003 16:21 UT 1/24 2004 0:15 UT exaggerated. 3 4:41 1 0:05 NASA / ESA / J. PARKER / P. THOMAS / L. MCFADDEN / M. MUTCHLER / Z. LEVAY 6 1:31 3 20:55 Binocular Comet Lulin 8 22:20 6 17:44 11 19:09 9 14:33 In late February and the Americas, while about 5th south-southwest of Saturn. beginning of March, Comet magnitude, it’s passing 3° And on the evening of 14 15:59 12 11:22 C/2007 N3 (Lulin) should north-northeast of Spica, then February 27th, it’s moving 17 12:48 15 8:12 brighten to 5th or even 4th on the evening of the 16th it’s within about 1° of Regulus. magnitude as it crosses Virgo 4° to Spica’s north-northwest. There’s little or no 20 9:37 18 5:01 and Leo, which are rising high On the evening of February moonlight during this 23 6:27 21 1:50 in the dark late-evening sky. 19th, look for the comet 3° time. For a ﬁ nder chart The comet has some southwest of Gamma Virginis. and more information see 26 3:16 23 22:40 notable conjunctions along On the night of February SkyandTelescope.com/ 26 19:29 the way. On the evening 23rd, near its peak brightness, CometLulin. ✦ A comparison-star chart for Algol is in last of February 15th for the Comet Lulin is passing 2° — Greg Bryant month’s issue, page 72. 29 16:18 60 March 2009 sky & telescope Copyright 2009, New Track Media, LLC. All Rights Reserved.opyright 2009, New Track Media, LLC. All Rights Reserved. C

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