SUNSET: 
The Fuzzy Face of Ceres
The first known asteroid, 1 Ceres, is also the largest body in the asteroid belt. These Hubble Space Telescope images, taken in ultraviolet light about 3 hours apart, reveal a vague, dark circular feature about 250 kilometers across. Astronomers propose to name it Piazzi, to honor the asteroid's discoverer.Courtesy Joel…
Mars Odyssey Arrives
An artist's depiction of the 2001 Mars Odyssey spacecraft firing its engine upon reaching Mars. The brightly colored landscape at upper right represents the surface-composition mapping that will be a major mission objective.Courtesy NASA/JPL. After cruising across 460 million kilometers of interplanetary space over 6½ months, NASA's 2001 Mars Odyssey…
New Eruption Offers a Taste of Io
A towering new volcano on Io, unknown prior to Galileo's close-range flyby on August 6th, created both a 700-kilometer-wide ring (left) and an umbrella-shaped plume extending to a height of at least 500 km (right). The nearby volcano Tvashtar Patera was unexpectedly dormant during the flyby.Courtesy University of Arizona and…
Deep Space 1 Spies Comet
Comet Borrelly, which orbits the Sun every 6.8 years, passed through perihelion on September 14th — just 8 days before Deep Space 1 flew past at close range. Georgia amateur Tim Puckett recorded Borrelly's coma and faint tail a half day later with his 30-centimeter telescope. After weeks of concern…
Astronomers Launch Pro-Am "Registry"
Years in development, a new online service allows experienced amateur observers and willing professionals to collaborate on scientific research projects.
Cassini Calls on Phoebe
Cassini's first rendezvous with a Saturnian moon was a date to remember.
NASA's O'Keefe Details Hubble Plans
NASA administrator Sean O'Keefe tells the American Astronomical Society that he wants to send a robot, rather than Space Shuttle astronauts, to service the Hubble Space Telescope.
Did an Impact Trigger the "Great Dying"?
Geoscientists think they've found the site of a giant impact off the Australian coast that nearly wiped out life on Earth 251 million years ago.
Far-Flung Planetoid Shatters Distance Record
The discovery of an ice world more than twice as far from the Sun as Pluto may change thinking about how the solar system formed.
Whirlwind Weekend of Irish Astronomy
In late September skygazers from across Ireland and the United Kingdom flocked to the 18th-annual Whirlpool Star Party.
Downpours on Ancient Mars?
A new computer model suggests that ancient Mars may have been deluged with rain following every major cratering event.
Mars Meets the Moon
Although lunar occultations of Mars aren't rare, the red planet loomed large during the dramatic meeting on July 17th.
Small Asteroids = Small Threat?
Two researchers argue that stony asteroids fall apart much easier when they slam into Earth's atmosphere — and thus are far less destructive — than previously thought.
Nozomi (Finally) Heads for Mars
Japan's first-ever planetary spacecraft should reach Mars in mid-December &$151; but will it be functioning when it gets there?
Neptune's Forecast: A Cloudy Summer
Although sunlight barely warms distant Neptune, bright clouds are building in the planet's sunny southern hemisphere.
NASA Sets Its Sites on Mars
With a mass of roughly 180 kilograms, NASA's Mars Exploration Rovers will be able to trek up to 100 meters per day during their three-month explorations. Each lander carries a suite of five instruments, collectively called Athena, and an abrasion tool for exposing fresh surfaces on rock faces.Courtesy NASA/JPL. After…
Too Few Lunar Meteorites
We find as many chunks of Mars lying on Earth as chunks of the Moon — even though the Moon is closer and loses pieces more easily. Something is amiss.
Jupiter's Weather Gets Clearer
During its flyby of Jupiter, the Cassini spacecraft found that Jupiter's weather is far more complex than previously thought.
Lunar Flash Doesn't Pan Out
A fresh-looking crater on the Moon seemed to confirm that a bright "impact" on the Moon was seen firsthand in 1953 — but new evidence proves otherwise.
