SUNSET: 
Ceres: The Wet Look
Mounting evidence suggests that the largest asteroid is hiding a large cache of water ice beneath its surface.
SMART 1's Dramatic Finale
Right on cue, a European spacecraft slammed into the lunar surface on September 3rd and created a flash on impact bright enough to be seen on Earth.
SMART 1 Awaits Its Fate
A European spacecraft will crash into the Moon on Saturday night, September 2nd, or Sunday morning, September 3rd — and amateur astronomers will be watching for the telltale flash. Many of the world's major observatories will try to record to the event too.
Why do the outer, gas-giant planets rotate faster than the inner, terrestrial planets?
Why do the outer, gas-giant planets generally rotate much faster than the inner, terrestrial planets? The reasons why some planets rotate as quickly as they do remain puzzling to planetary scientists. Most studies in this area have focused on the inner planets. Earth and Mars, which accumulated gradually from rocky…
What happened to the "spokes" in Saturn's rings?
In 1979 the Voyager spacecraft revealed “spokes” in Saturn’s rings. Yet recent images from Cassini have shown no spokes. What happened to them? Those spokes have kept planetary scientists scratching their heads for decades. It’s thought that the spokes are radial fingers of dark, extremely fine dust particles that become…
Take a "Sat-seeing" Tour
It’s a bird! It’s a plane! It’s the International Space Station! Learn how to spot Earth's artificial satellites.
What determines a moon's atmosphere? (Why is Titan's atmosphere so dense?)
Why is it that Saturn’s moon Titan has a dense atmosphere, yet Jupiter’s Ganymede and Callisto (about the same size as Titan) do not? Blame it on their parent planets. All three moons are a mixture of rocky materials and water ice, and the crystalline structure of ice is particularly…
How much space debris falls into Earth's atmosphere every year?
Has anyone ever calculated the combined tonnage of meteroids and space debris falling into our atmosphere yearly? Yes, but it's hard because different methods are needed for different particle sizes. Ground radar and exposed spacecraft surfaces are best for detecting the very smallest bits, whereas photographic surveys have been used…
How can I spot satellite triads?
While binocular observing from Northern California on August 19, 2004, at 6:33 Universal Time, I picked up a trio of satellites moving from the northwest to overhead and passing through Cygnus. I’m sure they were satellites, as all three turned reddish at the same time before disappearing into Earth’s shadow.…
History of Pro-Am Collaboration
Despite decades of observing in relative isolation from one another, professional and amateur astronomers began to come together in the 1980s.
Martian Ice: Wide and Deep
Mars Express's onboard radar sounder has spotted vast "glaciers" of ice under the Red Planet's surface.
Asteroid Smashup Yields Dust Shower on Earth
Deep-sea sediments provide conclusive evidence that the collision of two large asteroids about 8 million years ago showered Earth with a gentle rain of dusty debris.
Hayabusa Hits Paydirt
After several close calls that threatened to end the mission, a Japanese craft has landed on an asteroid and grabbed a sample of its surface.
Astro Image in the News: Massive Meteorite Found
A mammoth stony-iron meteorite, found buried on a Kansas farm, ranks among the world's largest.
Asteroid Lander Lost in Space
The Japanese spacecraft Hayabusa is ready to grab samples of asteroid Itokawa, but a tiny hopping lander failed to make it to the surface.
Hayabusa Closes In on Asteroid Itokawa
Now hovering just 7 km from its target, a Japanese spacecraft is readying to sample the surface — amid growing concerns about the craft's stabilization system.
Hayabusa Arrives at Asteroid Itokawa
After a 27-month interplanetary cruise under ion power, Japan's Hayabusa spacecraft finally reaches the small asteroid that will be its home for three months.
Orion Telescopes Sold to Imaginova
The headquarters of Orion Telescopes & Binoculars in Watsonville, California.Sky & Telescope photograph by J. Kelly Beatty. In a move that caught the astronomical community by surprise, today Imaginova Corp. announced its purchase of Orion Telescopes & Binoculars. Based in Watsonville, California, Orion is a major manufacturer and distributor of…
A Ringside Seat for Huygens's Arrival
Europe's Huygens probe descends to the surface of Titan on January 14th, just as Saturn is at its closest and brightest and ideally placed for observing.
Titan: "A World Apart"
Cassini's first brush with Saturn's giant moon revealed a diverse, geologically active landscape.
