SUNSET: 
Chinese Supernova Keeps its Secrets
Astronomers find hints of what kind of explosion caused a "guest star" spotted in ancient skies, but the case isn't closed.
"Blue Stragglers" Renewed by Stealing
Some deceptively youthful stars may find their fountains of youth in material they grab off other stars.
Lensed Light Used to Weigh Dark Matter
Astronomers use a novel method of weighing distant galaxies to measure their masses and find that there's more matter than the galaxies' light can easily explain.
Dark Energy's Early Fingerprints
Studying the effect of galaxy clusters on the background radiation from the early universe, University of Hawaii astronomers have added to the pile of evidence for dark energy.
Eta Carinae Prepares for X-ray Crash
Known for its mysteriousness, one of the galaxy's most massive stars gears up for its periodic pundit-perplexing event. Will Eta Carinae finally reveal its secrets?
Weighing Black Holes with a Thermometer
Astronomers use the 12-million-kelvin-blaze of a galaxy's central region to measure its supermassive black hole.
A Galactic Dead Zone
Astronomers find that the organic compounds common throughout our galaxy and others suddenly disappear along M101's outer edge.
Artificial Intelligence Aids Astronomers
Astronomers have designed a neural network that can determine the particulars of binary star systems by just examining their light curves — and it can do it really, really fast.
Are Jupiters Hard to Come By?
A recent survey of stars in the Orion Nebula Cluster reveals that less than 10% of stars there have enough material in their surrounding disks to form Jupiter-sized planets.
Faint Supernovae Remain Unexplained
A subclass of supernovae that fades much faster than expected reveals possible kinks in astronomers' theories of what causes these explosions.
Brown-Dwarf Binary Tests Theories
Recent calculations for a pair of failed stars add to astronomers' scant knowledge of brown dwarfs and will help set a reference point for future studies.
Water in Moon Dust Raises Questions
Traces of water recently found in glassy granules brought back 40 years ago by the Apollo 15 crew suggest scientists haven't quite figured out yet just how our Moon formed.
Mercury: The Incredible Shrinking Planet
During its first flyby of Mercury, NASA"s Messenger spacecraft found much less iron on the planet’s surface than expected and a cloud of ionized atoms — including water — caught up in the planet’s magnetosphere. And that’s just for starters.
Regulus’s Secret Companion
Astronomers confirm a low-mass star orbits the Lion’s heart, the bright blue star imaged here to the lower right. But what exactly is it?
Martian Dirt is Friendly to Life
The Phoenix lander's first wet chemical analysis of the Martian surface confirms water’s thumbprint and finds the kinds of inorganic minerals you'd have in a backyard garden.
The Most Massive Star Yet?
Searching the core of one of the densest young star clusters in the Milky Way, scientists may have beat out primetime TV in the search for the newest big star.
The Mystery of Saturn’s Double Aurorae
New infrared observations reveal a second auroral ring on Saturn that may help astronomers understand what causes the planet's aurorae in the first place.
Ulysses' Space Odyssey Ends on July 1st
The only space mission ever to study the Sun’s poles directly will turn off at month’s end after a long life of trial and triumph.
Hubble Looks into the Coma Cluster
The HST captures a pristine image of various galaxy types grouped together, but what is most intriguing is what the image doesn't reveal.
Moonlets Perturb Saturn’s Ring
New observations from Cassini show small satellites are responsible for Saturn's F ring looking a little frazzled.