Phobos Over Mars
13.03.1999

Hurtling through space a mere 3,000 miles above the Martian surface, the diminutive moon Phobos (below and left of center) was imaged against the backdrop of a large shield volcano by the Viking 2 Orbiter in 1977.

The Largest Rock Known
2.01.2000

There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid, moon, and comet nucleus. It is larger than any other rocky planet. (Nobody knows...

Deimos: A Small Martian Moon
15.11.1998

Mars has two tiny moons, Phobos and Deimos. Pictured above is Deimos, the smaller moon of Mars. In fact, Deimos is one of the smallest known moons in the Solar System measuring only 9 miles across.

A Supernova in the Whirlpool
21.04.1996

In 1994, a new star in a distant galaxy was seen by amateur astronomers, who alerted the world to their discovery of a supernova. Near the nucleus of spiral galaxy M51, popularly known...

LMC X-1: A Black Hole Candidate
30.12.1995

The strongest source of X-rays in the Large Magellanic Cloud originates from an unusually energetic binary star system. This strong source, dubbed LMC X-1, is thought to be a normal and compact star orbiting each other. Gas stripped of the normal star falls onto the compact star, heats up, and emits X-rays.

Hamlet of Oberon
31.01.1997

What's in a name? Since 1919, the International Astronomical Union has been charged with the task of establishing "conventional" nomenclature for planets, satellites, and surface features. For the remote Uranian system of moons, namesakes from Shakespearean works have been chosen.

A Supernova Starfield
9.02.1999

Bright stars don't last forever. A bright star similar to others in this field exploded in a spectacular supernova that was witnessed on Earth in 1987. The result is visible even today as unusual rings and glowing gas. The above picture is a composite of recent images taken over several years.

An Alaskan Volcano Erupts
7.06.2006

What is happening to that volcano? It's erupting! The first person to note that the Aleutian Cleveland Volcano was spewing ash was astronaut Jeffrey N. Williams aboard the International Space Station. Looking down...

Valles Marineris: The Grand Canyon of Mars
30.07.2006

The largest canyon in the Solar System cuts a wide swath across the face of Mars. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep.

The Mysterious Rings of Supernova 1987A
6.02.2000

What's causing those odd rings in supernova 1987A? In 1987, the brightest supernova in recent history occurred in the Large Magellanic Clouds. At the center of the picture is an object central to the remains of the violent stellar explosion.