Mercury: Planet of fire and ice

The MESSENGER spacecraft reveals Mercury to be a world with unexpected composition, an offset magnetic field, and permanently shadowed craters that may harbor ice.

Web Extra: Probing Mercury’s deepest secrets

Since the MESSENGER spacecraft entered orbit around the innermost planet in March, it has returned a treasure-trove of images and other data to eager scientists on Earth.

New clues to the Moon’s distant past

Two probes uncover a shrinking, water-rich lunar world beset by extreme conditions.

Web Extra: Watch LRO and LCROSS in action

NASA’s videos of its two famous lunar probes help provide a better sense of their abilities and accomplishments.

How astronomers make sense of starlight

Scientists learn what objects are made of, how hot they are, and even how fast the universe is expanding by analyzing their light.

Wander winter’s deep sky

Spectacular objects await you this season no matter your telescope’s size.

Web Extra: More winter objects to wander through

In the December 2011 issue of Astronomy, I wrote “Wander winter’s deep sky,” which was a guide to great celestial sights through five sizes of telescopes: 3- to 4-inch, 6- to 8-inch, 10- to 12-inch, 14- to 18-inch, and 20-inch and up. We didn’t have room enough to picture all the objects, so I thought I’d bring 10 more of them to you here. Enjoy!

Discover an asteroid!

In these days of professional sky surveys, amateur astronomers can still find minor planets. Here’s how one imager uncovered 11.

Visit Southern California’s top astronomy sites

From the discovery that the universe is expanding to building the next-generation Mars rover, Southern California harbors must-see locations for anyone interested in astronomy.

Web Extra: Explore more astronomy sites in California

The Golden State has many places for an astronomy fan to visit.

Astronomy tests Tele Vue’s new eyepiece line

Delos eyepieces feature generous eye relief, a wide field, and tack-sharp optics.