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.
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.
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.
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.
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.
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.
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
Bob Berman’s Strange Universe
Stephen James O’Meara’s Secret Sky
The Sky this Month
Glenn Chaple’s Observing Basics
Phil Harrington’s Binocular Universe