Abell 2142: Clash of the Galaxy Clusters
6.03.2000

Over the course of billions of years, whole clusters of galaxies merge. Above is an X-ray image of Abell 2142, the result of the collision of two huge clusters of galaxies, and one of the most massive objects known in the universe.

Colorful Light Pillars
2.09.2002

How can an aurora appear so near the ground? Pictured above are not aurora but nearby light pillars, a local phenomenon that can appear as a distant one. In most places on Earth...

Mercury: A Cratered Inferno
2.01.1999

Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock. Mercury's diameter is about 4800 km, while the Moon's is slightly less at about 3500 km (compared with about 12,700 km for the Earth). But Mercury is unique in many ways.

Colorful Light Pillars
5.03.2006

How can an aurora appear so near the ground? Pictured above are not aurora but nearby light pillars, a local phenomenon that can appear as a distant one. In most places on Earth...

Hydrogen, Helium, and the Stars of M10
30.06.2001

Stars like the Sun use hydrogen for fuel, "burning" hydrogen into helium at their cores through nuclear fusion. But what happens when that hydrogen runs out? For a while, hydrogen burns in a shell surrounding the stellar core and the star expands to become a red giant.

Anvil Cloud Over Sicily
18.02.2004

The cloud poses no danger to the building. Appearing to float above a remote monastery in Sicily, Italy, the anvil cloud's shape shows several classic cloud features. The cloud itself is composed of millions of very small droplets of water and ice.

Titan s Cryovolcano
10.06.2005

Investigators suspect the domed feature detailed above is an ice volcano, or cryovolcano, seen in infrared light through the hazy atmosphere on Saturn's moon Titan. Since Titan's surface temperature is around -180...

SDO: The Extreme Ultraviolet Sun
23.04.2010

Don't panic, the Sun has not gone wild. But this wild-looking portrait of the nearest star to planet Earth was made on March 30th by the recently launched Solar Dynamics Observatory (SDO). Shown in false-color, the composite view covers extreme ultraviolet wavelengths and traces hot plasma at temperatures approaching 1 million kelvins.

Habitable Worlds
3.03.2014

Is Earth the only known world that can support life? In an effort to find life-habitable worlds outside our Solar System, stars similar to our Sun are being monitored for slight light decreases that indicate eclipsing planets. Many previously-unknown planets are being found, including over 700 worlds recently uncovered by NASA's Kepler satellite.

Orion Launch
5.12.2014

Headed for two orbits of planet Earth and a splashdown in the Pacific, Orion blazed into the early morning sky on Friday at 7:05am ET. The spacecraft was launched atop a United Launch Aliance Delta IV Heavy rocket from Cape Canaveral Air Force Station in Florida.