SUNSET: 
Saltwater Ocean on Enceladus
Recent findings hint at the possibility of a saltwater ocean beneath Enceladus's icy surface.
Odd Couple: Phobos and Jupiter
Recently two very different bodies made a joint appearance, as viewed by the stereo camera aboard the European orbiter Mars Express.
Messenger Reveals Mercury Anew
Already a fourth of the way through its basic mission, NASA's well-equipped orbiter has found that the "Iron Planet" is far different than planetary scientists expected.
Meteorite Cooks Up Its Organic Brew
A dash of this and a pinch of that — slow cooked with water inside an asteroid — could have yielded a rich and diverse soup of organic matter. That's the remarkable new finding from careful analysis of the super-primitive Tagish Lake meteorite.
Dissecting Saturn's Big Storm
Scientists have combined images from Cassini and big telescopic eyes in Chile to understand Saturn's massive storm in ways never before possible.
Praising Arizona — II
S&T contributing editor Govert Schilling visits observatories in southern Arizona.
Praising Arizona — I
S&T contributing editor Govert Schilling visits observatories in southern Arizona
New Insights on Lunar Swirls
Comet impacts? Magnetic oddities? Crashed alien spaceships? Soon scientists hope to solve the longstanding mystery of bright swirls like Reiner Gamma on the lunar surface.
Messenger: Mercury's New Moon
The fleet-footed planet of the ancients has a new companion — a NASA spacecraft that will now call it home after a convoluted, 6½-year-long, 5-billion-mile interplanetary cruise.
What Makes Iapetus So Weird?
Now that scientists have puzzled out this moon's yin-yang appearance, they're tackling the cause of its out-of-round shape, slow spin, and bizarre equatorial ridge.
Is Water Flowing on Mars?
Spacecraft images are keeping an eye on little surface flows on Mars that show up in midsummer, then fade over time. It's the strongest suggestion yet that the Red Planet can get wet.
Remembering James Elliot, 1943–2011
The co-discoverer of Uranus's rings and Pluto's atmosphere has passed away at age 67.
Game Plan for NASA's Planetary Missions
If you had billions of dollars to spend on interplanetary spacecraft, which ones would you choose and why? After an exhaustive, two-year assessment, a blue-ribbon panel turned over its top picks to NASA.
A New Take on the Spotless Sun
A trio of researchers believe a slow-moving conveyor belt between the Sun's equator and its poles is responsible for the recent years-long absence of sunspots.
Double Whammy on Mars
On January 10th, NASA's Mars Reconnaissance Orbiter spotted twin craters joined at the rim — the consequence of equal-size halves of a single object striking the planet together.
A Half-Gigabyte View of the Moon
This week NASA scientists unveiled a view of the lunar nearside that measures an astounding 24,000 by 24,000 pixels.
Stardust's Date With Comet Tempel 1
Low on fuel but right on the money, NASA's Stardust spacecraft visited its second comet earlier today. Scientists are eager to see the crater supposedly punched in the icy nucleus 5½ years ago. One small problem: there's not much of a crater to see.
A New Light on Jupiter
With the help of Jupiter's moon Europa, astronomers have imaged the re-emerging South Equatorial Belt in unprecedented detail.
The Sun Has Nothing to Hide
For the first time, scientists can examine the front and back sides of our star at the same time, thanks to a pair of distant Sun-watching spacecraft.
Jupiter Swallows an Asteroid
Some careful spectroscopic detective work has led astronomers to conclude that a cruise-ship-size asteroid — not a small comet — smacked into the king of planets in July 2009.
