SUNSET: 
The Source of the Dinosaurs' Asteroid
Did a colossal collision in the asteroid belt 160 million years ago doom the dinosaurs? A just-published analysis argues strongly for exactly that.
Mira's Marvelous Tail
Mira, the closest and brightest of the red long-period variable stars, has thrown off a gassy hood and a comet-like tail so big that if you could see them, they would overflow your telescope's field of view.
A Ringside View of Uranus
Astronomers have assembled an armada of telescopes to observe Uranus in a way that hasn't been possible since the 1960s.
The New Largest Telescope in the World
With an aperture of 10.4 meters, Spain's new Gran Telescopio Canarias is about to assume the title.
Overgrown Planet, or Dwarf in the Desert?
Astronomers have uncovered a fascinating heavy object orbiting close to its star. The problem is, they aren't sure what to call it.
Goodbye, Pluto. Hello, "Dwarf Planets"!
It's official: our solar system has eight planets, and Pluto is not one of them according to the International Astronomical Union.
Giant Telescopes of the Future
Telescopes as large as 20, 30, and even 100 meters are now on the drawing boards.
Galaxy Maps Reveal Nature of Universe
The latest results from two comprehensive galaxy surveys independently confirm the important role of dark matter and dark energy in the evolution of the cosmos.
A Black Hole Swarm
In this Chandra X-ray Observatory image of the galactic center, the four labeled sources are bright and variable. They are probably binary systems consisting of a stellar-mass black hole and a normal star. The Milky Way's central black hole, known as Sagittarius A*, is the bright spot above source C.Courtesy…
A Planet Found Through Asteroid Belts
Orbiting Beta Pictoris farther than Saturn orbits the Sun, an unseen planet is apparently shaping the star's asteroid belts.
LOFAR: A Giant Radio Telescope Takes Shape
Fifteen thousand humble little antennas will work in concert to form one of the world's most powerful astronomical instruments.
Astro News Briefs: May 31–June 6
Tiny-tiny galaxies and activity minima in Sun-like stars.
Nearby Remnant of a Gamma-Ray Burst?
What looks like a supernova remnant on the far side of the Milky Way could be the shattered remains of something bigger.
Seeing the Very First Galaxies
The first stars to light up the universe after the Big Bang did not appear in a simple, expected way.
Spitzer Exposes Mystery Holes
Taking its deepest-yet look into the infrared sky, the Spitzer Space Telescope pulls some mysterious objects out of hiding.
Mysteries of the North Star
Polaris is not only a variable star, its variations are varying. And no one quite knows why.
Lensed Quasars Hit the Charts
In the span of three weeks, astronomers twice smashed a record that had stood since 1979.
Making Planetary Nebulae
It make a dying double star to create a planetary nebula — and to make it light up.
Hubble's Really Big Picture
By stitching together 78 high-resolution Hubble Space Telescope photos, astronomers have created Hubble's widest "deep field."
Finding Our Nearest Stellar Neighbors
Astronomers are trying to hunt out everything that exists within 32 light-years of Earth.