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 2008
Nucleus of Comet Wild 2
Bill Cooke of NASA's Marshall Space Flight Center answers this question.
Published: February 21, 2008
Calabi-Yau manifold
Exploring the cosmic microwave background may give scientists insight into the shape of inner space.
By Francis Reddy // Published: February 21, 2008
Hydra
The sky's largest constellation sports many binocular gems to fill your nights.
By Phil Harrington // Published: February 21, 2008
Active Sun
Use this guide to determine the type of sunspot you're observing.
By Michael E. Bakich // Published: February 21, 2008
Pencil Nebula
Hubble images take you to the heart of the Vela Supernova Remnant.
By Daniel Pendick // Published: February 21, 2008
Chajnantor plain
The Atacama Large Millimeter Array will provide radio astronomers an unprecedented combination of sensitivity and resolution.
By Richard Talcott // Published: February 21, 2008
Sunspot 898
Add precision to your sunspot counts.
By Michael E. Bakich // Published: February 21, 2008
The Cincinnati Observatory
The Antique Telescope Society convenes a workshop at the Cincinnati Observatory Center to address problems facing historic observatories.
By Jeremy McGovern // Published: February 21, 2008
M13
Download this Meade Autostar tour and you'll be observing great globulars in no time.
By Michael E. Bakich // Published: February 21, 2008
Methane hydrate ice
Scientists can choose from a growing menu of proposed causes for the end-Permian extinction. Here are the leading contenders.
By Joel Davis // Published: February 21, 2008
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