1121–1140 of 1,212 results
Ceres in cutaway

Solar System

Ceres: The Wet Look

Mounting evidence suggests that the largest asteroid is hiding a large cache of water ice beneath its surface.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Saturn on July 18, 2015

Astronomy Questions & Answers

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…

Spokes in Saturn's rings

Science-based Q&A

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…

International Space Station

Celestial Objects to Observe

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.

Titan steals the show

Astronomy Questions & Answers

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…

Perseid fireball

Hobby-based Q&A

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…

Astronomy Questions & Answers

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.…

1998 Pro-Am Workshop

Pro-Am Collaboration

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.

Astronomy & Observing News

Martian Ice: Wide and Deep

Mars Express's onboard radar sounder has spotted vast "glaciers" of ice under the Red Planet's surface.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Astronomy & Observing News

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.

Astronomy & Observing News

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…

Astronomy & Observing News

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.

Astronomy & Observing News

Titan: "A World Apart"

Cassini's first brush with Saturn's giant moon revealed a diverse, geologically active landscape.