INTRODUCINGINTRODUCING THETHE NEWNEW LX65LX65 SERIESSERIES At Meade, we believe the universe should be accessible to all and available at a moment’s notice. The new LX65 series telescope does this by combining advanced features and premium optics in an easy-to-use portable telescope system. This versatile GoTo telescope features our AudioStar® hand controller, all-metal worm-drive gearing, removable optical tube with Vixen-style dovetail, and secondary mounting saddle for attaching an additional OTA. The secondary saddle allows you to view objects both in wide field or close up and is ideal for astronomy outreach and is sure to impress anyone with its technology and optics. 6” Maksutov & 80mm APO* *(sold separately) Available with a 5" Maksutov 6" Maksutov 6" ACF or 8" ACF SINGLE-FORK ARM MOUNT - Sturdy single-arm design allows you to mount two optical tubes at once. The second saddle is fully adjustable allowing both tubes to be precisely pointed at the same object. PORTABLE BUILD - This portable scope breaks down into two compact pieces and does not require any tools. With its built-in carry handle, transporting the LX65 to your favorite dark-sky location is a breeze! 2nd Saddle with 7 lb. AUDIOSTAR® HAND BOX - Its 30,000-object database can take you on Payload! a guided tour of the night sky's best objects. With its built-in speaker, you can learn so much about the objects you're viewing! Focus Camera | focuscamera.com Agena | agenaastro.com Astronomics | astronomics.com Optics Planet | opticsplanet.com Adorama | adorama.com High Point Scientific | highpointscientific.com OPT Telescopes | optcorp.com B&H Photo Video | bhphotovideo.com Woodland Hill Camera | whcamera.com Online Content Code: ASY1808 Enter this code at: www.astronomy.com/code AUGUST 2018 to gain access to web-exclusive content VOL. 46, NO. 8 24 CONTENTS KELLY ROEN : ASTRONOMY FEATURES ON THE COVER 22 33 50 The past 45 years have brought COVER STORY Inflation leaves The weird mystery incredible explorations and discoveries in astronomy, The 10 its mark of dark energy planetary science, and cosmology. biggest things YEARS Alan Guth’s remarkable hough it dominates the OF ASTRONOMY theory provides a master universe, dark energy is the in astronomy MAGAZINE For nearly half a key to the universe we see biggest discovery we don’t century, the world’s today. MARA JOHNSONGROH understand. LIZ KRUESI leading title on astronomy and 53 space has reported mesmerizing 36 COLUMNS science. DAVID J. EICHER Sky This Month Exoplanets burst Prime time for the Perseids. onto the scene Strange Universe 12 BOB BERMAN 24 MARTIN RATCLIFFE AND Since their discovery in The Red Planet revealed ALISTER LING 1992, planets outside our solar For Your Consideration 16 More than a dozen spacecrat system have been found around JEFF HESTER have shown Mars to be a 38 thousands of stars in the galaxy. KOREY HAYNES Observing Basics 18 wonderfully diverse world StarDome and GLENN CHAPLE with hidden stores of water. Path of the Planets 56 JOHN WENZ RICHARD TALCOTT; Secret Sky 64 ILLUSTRATIONS BY ROEN KELLY Pluto finds its place STEPHEN JAMES O’MEARA 27 No longer a lone world at the Binocular Universe 66 edge of the solar system, Pluto Shining light 44 PHIL HARRINGTON on black holes Decoding the cosmic is the brightest and best-studied It took 200 years to ind the irst member of a vast throng of microwave background Kuiper Belt objects. JOHN WENZ QUANTUM GRAVITY black hole. Now we know they’re he Big Bang let behind a unique Snapshot 9 everywhere. FRANCIS REDDY signature on the sky. Probes 59 Astro News 10 30 such as COBE, WMAP, and Glimpsing Planck taught us how to read it. gravitational waves Voyager’s Grand Tour LIZ KRUESI IN EVERY ISSUE he twin probes explored more he screams of colliding black planets, discovered more moons, 47 holes allow astronomers to study From the Editor 6 the universe in a whole new way. and ofered more breaking Hubble’s Astro Letters 8 news than any other spacecrat. ROBERT NAEYE New Products 62 MICHAEL E. BAKICH astounding legacy NASA’s inest instrument has cap- 68 Advertiser Index 65 tured more images and generated Ask Astro Reader Gallery 70 more research than any telescope he expanding universe. in history. MICHAEL E. BAKICH Breakthrough 74 Astronomy (ISSN 0091-6358, USPS 531-350) ONLINE is published monthly by Kalmbach Media Co., 21027 Crossroads Circle, P. O. Box 1612, Waukesha, WI 53187–1612. Periodicals post- FAVORITES age paid at Waukesha, WI, and additional offices. POSTMASTER: Send address changes to Astronomy, P.O. Box 62320, Tampa, Fla. 33662-2320. Go to www.Astronomy.com Dave’s News Picture Venus Globe Canada Publication Mail Agreement #40010760. for info on the biggest news and Universe The latest of the Day Get the observing events, stunning photos, The inside updates from Gorgeous hottest globe scoop from the science photos from around. informative videos, and more. the editor. and the hobby. our readers. 4 ASTRONOMY • AUGUST 2018 Make Some History with a Tele Vue Telescope of Your Own! 'HGLFDWHGWR &UDIWVPDQVKLS $XWR$GMXVWLQJ *72 0RWRU*HDUER[HV $EVROXWH(QFRGHU 2SWLRQ 9'& Image courtesy of Don Bruns Illustration of the image identifying qualifying stars to measure positional deviation due to the Sun’s gravity. It took about two-and-a-half minutes during totality of the 2017 total solar eclipse for Dr. Don Bruns to make history. Using a Tele Vue-NP101is, Don confirmed Einstein’s prediction of starlight deflection to an accuracy beyond all previous optical attempts. Whether you make scientific or *72&3 family history, the heirloom quality, 60mm to 127mm APO refractors we build in New &RQQHFWLYLW\ York are “imagination-limited” instruments. What will you do with yours? Read Don’s and other Tele Vue owners’ stories on our blog at Televue.com. ZZZDVWURSK\VLFVFRP 0DFKHVQH\3DUN,/86$ @televueoptics 32 Elkay Drive, Chester, NY 10918 845.469.4551 TeleVue.com 3K PRESENTS WWW.ASTRONOMY.COM 5 FROM THE EDITOR BY DAVID J. EICHER Editor David J. Eicher Art Director LuAnn Williams Belter EDITORIAL Senior Editors Michael E. Bakich, Richard Talcott Production Editor Elisa R. Neckar Associate Editors Alison Klesman, Jake Parks Copy Editor Dave Lee Astronomy Editorial Assistant Amber Jorgenson ART Graphic Designer Kelly Katlaps Illustrator Roen Kelly Production Specialist Jodi Jeranek marks 45 CONTRIBUTING EDITORS Bob Berman, Adam Block, Glenn F. Chaple, Jr., Martin George, Tony Hallas, Phil Harrington, Korey Haynes, Jeff Hester, Liz Kruesi, Ray Jayawardhana, Alister Ling, Steve Nadis, Stephen James O’Meara, Tom Polakis, Martin Ratcliffe, Mike D. years Reynolds, Sheldon Reynolds, Erika Rix, Raymond Shubinski SCIENCE GROUP Executive Editor Becky Lang Design Director Dan Bishop ith this issue, the scientific results, in EDITORIAL ADVISORY BOARD Buzz Aldrin, Marcia Bartusiak, Timothy Ferris, Alex Filippenko, Astronomy detail, that streamed back Adam Frank, John S. Gallagher lll, Daniel W. E. Green, William K. Hartmann, Paul Hodge, Edward Kolb, Stephen P. Maran, Brian magazine cel- from the New Horizons May, S. Alan Stern, James Trefil Webrates its 45th mission to Pluto and its anniversary. family of oddball moons. Kalmbach Media A young college graduate If you’re more about CEO Dan Hickey Vice President, Content Stephen C. George named Stephen Walther the nuts and bolts of Vice President, Consumer Marketing Nicole McGuire took his passion for astron- astronomy in our gal- Art and Production Manager Michael Soliday First issue, August 1973 Advertising Sales Director Scott Redmond omy and, in the summer axy and beyond, check out Circulation Director Liz Runyon New Business Manager Cathy Daniels of 1973, founded a popular the explosive history of exo- Retention Manager Kathy Steele magazine on the subject. planet discoveries. In 1992, cosmic microwave back- Single Copy Specialist Kim Redmond By the 1980s, the magazine ADVERTISING DEPARTMENT we knew of one planetary ground radiation, the after- Phone (888) 558-1544 had become the most widely system outside our own. glow of the Big Bang itself. Advertising Sales Manager Steve Meni Advertising Sales Representative read periodical on the sub- Now astronomers know of How about deciphering the Dina Johnston, [email protected] ject. It still holds that title more than 3,700 exoplanets mystery of dark energy? And Ad Services Representative Christa Burbank, [email protected] today. in more than 2,800 plan- you can get the latest on RETAIL TRADE ORDERS AND INQUIRIES I never met Steve; in 1977, etary systems around us in gravitational waves, those Selling Astronomy magazine or products in your store: Phone (800) 558-1544 he died suddenly of a brain the galaxy. Most of these ripples in space-time from Outside U.S. and Canada (262) 796-8776, ext. 818 tumor. I joined the fold in discoveries were made with colliding black holes and Fax (262) 798-6592 Email [email protected] 1982, and the editorial staff the Kepler space telescope. neutron stars. Website www.Retailers.Kalmbach.com has been holding up the You can also check out If that isn’t enough for CUSTOMER SALES AND SERVICE Phone (877) 246-4835 same level of quality report- the highlights from the you, please think about the Outside U.S. and Canada (813) 910-3616 Customer Service [email protected] ing ever since Steve’s days. Hubble Space Telescope, folks who brought this issue Digital [email protected] To commemorate the which has revolutionized to you, for just a moment. Back Issues [email protected] magazine’s anniversary, the our view of the cosmos in This is an “alumni” issue, CONTACT US Ad Sales [email protected] editors have assembled a multiple ways. And how written mostly by former Ask Astro [email protected] Books [email protected] special package looking at about delving into the his- editors of the magazine who Letters [email protected] astronomy’s greatest hits of tory of black holes? 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