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.
March 2004
Icy Mars
By Michael E. Bakich // Published: February 1, 2004
Although to date they've managed to identify only two sources of neutrinos from beyond Earth, physicists continue to search for these elusive particles.
By Richard Talcott // Published: February 1, 2004
NGC4261C
By Richard Talcott // Published: February 1, 2004
NGC 2243
For these star clusters, distance is the key to longevity.
By Ken Croswell // Published: February 1, 2004
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