How we mapped the Milky Way

After a centuries-long mystery, scientists now understand our galaxy’s spiral shape. But there’s more to unravel.

Web extra: How a scientist discovered we lived in one galaxy of many

Until 84 years ago astronomers thought the Milky Way Galaxy was the entire universe. Then they found that fuzzy objects in the sky were galaxies themselves.

Seeking ground truth on Mars

Under the watchful eye of five spacecraft, the Red Planet’s surface reveals weather and climate patterns and the complex history of water and ice.

Epsilon Aurigae: Astronomy’s longest-running mystery show

A huge, unknown object is dimming this supergiant star’s light, just as it did 27 years ago. New technology may soon tell us what it is.

Web extra: Citizen science and Epsilon Aurigae

Amateur observers can make important contributions to the scientific observing campaign focusing on Epsilon Aurigae.

Take the Ghost Hunt challenge

This Halloween season, grab your telescope and scare up these spooky objects.

Web extra: The Ghost Hunt’s 109 targets

This Halloween season, grab your telescope and scare up these spooky objects.

Explore 12 great lunar targets

Sharpen your observing skills on the Moon’s craters, lava flows, and an elusive letter X.

Web extra: See the Lunar X

Put this lunar target on your list in the next few years.


This Month in Astronomy
Beautiful Universe
Web Talk
Bob Berman’s Strange Universe
David H. Levy’s Evening Stars
Astro News
The Sky this Month
Glenn Chaple’s Observing Basics
Advertiser Index
Stephen James O’Meara’s Secret Sky
Telescope Insider
New Products
The Cosmic Grid
Deep-sky Showcase
Reader Gallery