SUNSET: 
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.
Diving Globular Cluster Makes a Starry Splash
Did a globular star cluster passing through the Milky Way cause new stars to form?
Refining the Cosmic Recipe
The Sloan Digital Sky Survey has helped provide astronomers with a more detailed map of the universe.
Cassini Proves Einstein Right — So Far
Radio links with the Cassini spacecraft show Einstein's general theory of relativity to be correct to one part in 40,000. But new physics could show up just a little beyond.
Monster Gamma-Ray Burst
A few days ago we got hit by the nearest major gamma-ray burst ever. It was bright enough that many amateur astronomers imaged it.
Hubble Captures a Protoplanetary Disk
Spiral rings appear in a young star's dusk disk that's ten times larger than our solar system.
Interstellar Reflections
New images from the Hubble Space Telescope reveal unprecedented detail in a light echo expanding around an explosive variable star in Monoceros.
Did Pluto Take a Punch?
A Hubble Space Telescope image snapped in 1994 easily resolves Pluto and its moon, just 0.9 arcsecond apart. Charon's orbit is about 39,300 kilometers in diameter — but astronomers are surprised that it's not a perfect circle.Courtesy R. Albrecht (ESA/ESTEC) and NASA. If David J. Tholen (University of Hawaii) is…
Looking for HEROs
The light from a very distant Hyper-Extremely Red Object, designated HERO1, has been redshifted so much that it can be seen in the near-infrared (right) but not at visible wavelengths (left). HERO1 is located in the sky very close to a radio source, known as 53W002, that is more than…
Super Sunspot Images
Using adaptive optics, a new solar telescope in the Canary Islands is taking the best-ever pictures of the Sun.
Star Speeds Around Milky Way's Black Hole
Astronomers have clocked a star orbiting the black hole at the Milky Way's center, revealing its mass.
Making Millisecond Pulsars
A three-hour long burst on a neutron star has confirmed many long-suspected fact about the dense, spinning stars.
Are Dormant Quasars Throwing "Baseballs" at Us?
Ultrahigh energy cosmic rays may come from quasars that were thought to be retired.
Closing In on Neutrino Properties
The heart of the Sudbury Neutrino Observatory is an acrylic sphere filled with heavy water and surrounded by photomultiplier tubes. These detect flashes of light produced when neutrinos interact with the water. This fisheye view was taken from beneath the sphere before the bottom panel of detectors was installed.Courtesy Ernest…