Astronomy (USA) - March 2013 
English | 80 pages | PDF | 22.3 MB

FEATURES
22 How astronomers know the universe's age
28 COVER STORY A new eye on the violent universe
34 Ask Astro Saturn's weird hexagon.
36 The Sky this Month Comet fever strikes.
38 StarDome and Path of the Planets
44 China's race to study the cosmos
50 Explore spring's best deep-sky objects
56 A day with two dawns 
60 Get ready for Comet PANSTARR 
64 Stellarvue's 6.3-inch refractor field-tested

COLUMNS
Strange Universe 11
BOB BERMAN
Observing Basics 1 4
GLENN CHAPLE
Secret Sky 18
STEPHEN JAMES O'MEARA
Cosmic Imaging 66
TONY HALLAS
Astro Sketching 68
ERIKA RIX

QUANTUM GRAVITY 
Snapshot 9
Breakthrough 10
Astro News 12

IN EVERY ISSUE 
From the Editor 6
Letters 11, 18,66
Web Talk 20
New Products 67
Advertiser Index 71
Reader Gallery 72
Final Frontier 74