Year of the Comet
Comet C/2011 L4 (PANSTARRS)

PANSTARRS information

Comet C/2012 S1 (ISON)

ISON information

Web Extras
Go deeper into the stories of Astronomy magazine. These online features bring you additional research, interviews, photos, and more our editors turned up while creating the stories for this issue.
June 2008
Center of NGC 6397
University of Illinois Professor Emeritus James Kahler explains this process.
Published: April 23, 2008
Orbiting Earth
NASA now tracks more than 10,000 pieces of junk orbiting Earth — and it took humans just 50 years to create this mess.
By Richard Talcott // Published: April 23, 2008
ISS
Satellite-watching was more than a hobby 50 years ago.
By Phil Harrington // Published: April 23, 2008
Gamma-ray Burst
Astronomers call gamma-ray bursts the biggest bangs since the Big Bang. NASA animator Dana Berry shows you how one works.
Published: April 23, 2008
Watch for the equivalent of 5 billion years as the merger of the Milky Way and the Andromeda Galaxy results in the birth of a single elliptical galaxy: Milkomeda.
Published: April 23, 2008
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