Is there something we don’t know about gravity?

Spacecraft flybys and the Moon’s orbit aren’t following predictions. Whatever is causing this could usher in a new theory of gravity.

Web extra: What can’t be causing the gravity anomalies

Scientists rule out some explanations for these strange occurrences.

Surprises from MESSENGER’s historic Mercury flyby

The MESSENGER spacecraft flew past Mercury in October, revealing landscapes never seen up close before.

Web extra: Message from Mercury

The MESSENGER spacecraft flew past the innermost planet October 6, giving scientists their second close look at Mercury in 2008.

Cassini flies through Enceladus’ geysers

The Cassini spacecraft flew past Saturn’s moon Enceladus twice in October, diving into its water-rich plume and imaging its dynamic surface.

Web extra: Inside Saturn’s erupting moon

The Cassini spacecraft flew past Enceladus once in August and twice in October, returning some of the sharpest images of the active moon yet.

How the Spitzer Space Telescope unveils the unseen cosmos

NASA’s flagship infrared eye in the sky has probed hidden corners of the universe for 5 years. Spitzer chief scientist Michael Werner shares some of the telescope’s greatest discoveries.

Web extra: Explore the Spitzer Space Telescope’s greatest scientific hits

The structure of star-forming regions, the recipe of a grand design spiral galaxy, and the look of the Milky Way’s center all made the list.

Discover galaxy groups and clusters

With an 8-inch or larger scope and a dark sky, go after these distant citizens of the cosmos.

Web extra: More galaxy groups to observe

Add another 10 to the list from “Discover galaxy groups and clusters.”

How to build a backyard observatory

A permanent telescope setup gives you fast and easy access to the sky.

Web extra: Choose the right dome for your needs

Download Contributing Editor Mike D. Reynold’s article about three ready-made domes to help you with your observatory purchase.

DayStar’s Quantum filter reveals the Sun

With solar activity on the rise, now may be the time to invest in a Hydrogen-alpha filter.


This Month in Astronomy
Beautiful Universe
Bob Berman’s Strange Universe
Stephen James O’Meara’s Secret Sky
Astro News
The Sky this Month
Glenn Chaple’s Observing Basics
Phil Harrington’s Binocular Universe

Messier madness

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