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.
April 2011
Orbiters around Mercury
NASA’s ambitious MESSENGER spacecraft will have company by the end of this decade, when the BepiColombo mission reaches the innermost planet.
By Richard Talcott // Published: February 21, 2011
Northern-lights
Iceland isn’t alone in offering dramatic views of the northern lights.
By Bill Andrews // Published: February 21, 2011
Gliese-581g
Studying the atmospheres of earthlike planets may be a few years in the future, but astronomers are analyzing weather on the largest worlds now.
By Liz Kruesi // Published: February 21, 2011
Sombrero-Galaxy
Enjoy more images of bright sky treats you can see through your binoculars.
By Michael E. Bakich // Published: February 21, 2011
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