SUNSET: 
Outer-Planet Moons Found — and Lost
A decade ago, astronomers used big scopes and deep exposures to find dozens of new moonlets around Jupiter and Saturn. But due to orbital uncertainties, 17 of them appear to be lost.
Vesta: A Study in Black and White
NASA's Dawn spacecraft is scrutinizing the second-largest asteroid from close range. Yet some aspects of Vesta's surface — especially splashes of very bright and very dark material — are puzzling.
Did the Moon Come From Earth?
New findings show that the Moon might have incorporated more of Earth when it formed than previously thought — a problem for the widely accepted "big splat" hypothesis.
Exciting Event on Mars!
Observers are reporting an unusual event on the Red Planet, well placed for western U.S. residents this evening.
March Madness on Mercury
After a full year of scrutiny by NASA's Messenger orbiter, the innermost planet is revealing itself to be unique — and downright confounding — to the project's scientists.
How Big is the Sun, Really?
By carefully recording the track of Mercury when it crossed the solar disk in 2003 and 2006, observers have measured the Sun's diameter more accurately than ever before.
WISE's Grand View of the Infrared Sky
In just 10 months during 2010, an orbiting observatory meticulously recorded a "heat map" of the entire celestial sphere, revealing unseen beauty in the Milky Way and providing astronomers with a catalog of more than a half billion celestial objects.
Smooth Sailing on Titan
Waves don't grow much — if at all — on Saturn's moon Titan. However, the calm lakes and seas might see some surface wrinkles in a few years when the northern hemisphere's summer arrives.
A Potpourri of Lunar Results
It's been nearly 40 years since Apollo astronauts last set foot on the lunar landscape. Yet, as a sampling of recent research efforts shows, we're a long way from answering all our questions about the Moon's formation and evolution.
Mars and Moon: Not Dead Yet?
The Martian and lunar surfaces were thought to be geologically dead. But twitches of recent activity are turning up in extreme closeups from orbiting spacecraft.
New Evidence for Ancient Martian Ocean
For decades planetary scientists have speculated about whether a huge depression that dominates the northern hemisphere of Mars was once flooded with water eons ago. Now radar soundings are showing that the answer might be "yes".
Wanted: Meteorites from Mercury
Dynamical oddsmakers insist that several samples of the innermost planet, blasted into space from fresh craters such as Mena, should be lying somewhere on Earth. So where are they?
GRAIL's Twins Safely Reach the Moon
Braking rockets fired on cue yesterday and today, placing twin spacecraft in lunar orbit. In the coming months, they will exploit the Moon's own gravity to revolutionize what we know about the lunar interior.
Pseudo-moons Orbit Earth
Temporary satellites are frequently caught from Earth's neighborhood and may make regular passes at being moonlets. But the objects only stick around long enough to orbit a few times before the Moon kicks them back out into the cold.
Comet Lovejoy: A Solar Survivor
The odds were stacked against it, but a comet discovered just two weeks ago has passed just 116,000 miles from the Sun's surface and — like a celestial phoenix — reemerged into view. Here's the latest on what veteran observer John Bortle calls "one of the most extraordinary events in cometary history."
Asteroids, Planets, and Moons, Oh My
This week’s meeting of the American Geophysical Union brought together a variety of interesting science results, from water on Mars to the Sun’s effect on the Moon’s surface. Here’s a selection of curiosities for your perusing pleasure.
Voyagers Detect Missing Signal
The Voyager spacecraft have observed long-sought emission from the Milky Way while traveling through the outermost reaches of the Sun’s influence.
Europa's Subsurface Lakes
Extensive lens-shaped lakes beneath the surface of Jupiter's moon Europa may explain strange features spread across the satellite's ice shell.
Hi-and-Bye Asteroid Creates a Buzz
The asteroid 2005 YU55 flew by last night exactly on track, capturing the attention of professional astronomers around the world and delighting well-prepared backyard observers.
Sunspot Points at Earth
A huge solar blemish mars the Sun’s disk, in perfect view for Earth-based observers.
