How comets shaped history

In ancient skies, a comet’s sudden appearance provided both spectacle and portent — and savvy leaders took advantage.

Web extra: History’s greatest comets

Scroll through the past to see just how good a comet can be.

Journey to the heart of the Milky Way

Astronomers know a supermassive black hole anchors our galaxy’s core. But they struggle to understand the origins of fast-moving stars that swarm it.

Web extra: The black-hole hostages of Sagittarius A

Did a medium-sized black hole drag a cluster of hot young stars to the Milky Way’s core?

On the trail of hydrogen’s heavy sibling

With twice the mass of ordinary hydrogen, deuterium plays a weighty role in trying to comprehend the early universe, galactic evolution, and life’s extent.

Where has all the water gone?

New results from Mars Reconnaissance Orbiter suggest the Red Planet’s past may not have been so warm and wet after all.

Web extra: Revealing the Red Planet’s secrets

The High Resolution Imaging Science Experiment onboard the Mars Reconnaissance Orbiter continues to amaze scientists with its detailed images.

Illustrated: Explore Jupiter’s moons

Tenuous dust rings, glowing gas clouds, and a ring of plasma arise from Jupiter’s closest moons.

Observe winter’s forgotten star clusters

Begin your observing year with 16 bright, but little-known, open clusters.

Web extra: Enjoy more great winter open clusters

Your tour of great open star clusters is just beginning.

The darkest sky under the stars

Observing and imaging are top priorities at Arizona Sky Village, a remote community that may be amateur astronomers’ paradise.

Meade’s mySKY teaches you the stars

Beginning astronomers take note: You can identify celestial objects like a pro.


This Month in Astronomy
Web talk
Bob Berman’s strange universe
Glenn Chaple’s observing basics
Phil Harrington’s binocular universe

Meet the colorful Gemini twins

Stephen James O’Meara’s secret sky
Astro news
The sky this month
New products
Advertiser index
Reader gallery