Triton: Neptune's Largest Moon
23.11.1997

On October 10th, 1846, William Lassell was observing the newly discovered planet Neptune. He was attempting to confirm his observation, made just the previous week, that Neptune had a ring. But this time he discovered that Neptune had a satellite as well.

Ski Mars
1.04.1999

These brightly reflecting fields of snow or frost are on the slopes of a crater rim in the northern hemisphere of Mars. They are 500 meters or so long and have lasted through about eight months of the Red Planet's spring and summer weather.

A Spherule from Outer Space
22.03.2000

When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads. Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions.

Sand Dunes Thawing on Mars
3.03.2008

What are these strange shapes on Mars? Defrosting sand dunes. As spring now dawns on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured above, are beginning to thaw. The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas.

White Rock Fingers on Mars
30.10.2011

What caused this unusual light rock formation on Mars? Intrigued by the possibility that they could be lakebed dried-up, detailed studies of these fingers now indicate a more mundane possibility: volcanic ash. Studying the exact color of the formation indicated the possible volcanic origin.

A Huge Solar Filament Erupts
31.07.2016

Filaments sometimes explode off the Sun. Featured, a huge filament had been seen hovering over the Sun's surface for over a week before it erupted late in 2010. The image sequence was taken by the Earth-orbiting Solar Dynamics Observatory (SDO) in one color of ultraviolet light.

Globular Cluster Omega Centauri
4.10.1996

Does an old, red globular cluster have any hot, blue stars? The rightmost picture, taken by the Ultraviolet Imaging Telescope in ultraviolet light, shows that indeed it does. Pictured, Omega Centauri is the largest known globular cluster in our Galaxy, containing well over a million stars.

Jupiter: The Great Yellow Spot
11.03.1997

What happened to Jupiter's Great Red Spot? Operating at a chilly 55 degrees Kelvin, the Galileo Spacecraft's Near Infrared Mapping Spectrometer (NIMS) recorded this composite image of Jupiter's Great Red Spot in late June 1996.

Mars: Twin Peaks In Stereo
14.07.1997

Get out your red/blue glasses and gaze across the surface of Mars in stereo. You are looking south of west across an ancient flood channel, Ares Vallis, landing site of the Mars Pathfinder.

A Presidential Panorama of Mars
22.07.1997

Scroll right to unfold the latest panorama of the surface of Mars. For best viewing, click and hold on the right arrow icon at the bottom of your browser window. This image, released yesterday and dubbed a "presidential panorama" by the Mars Pathfinder team, shows in colorful detail the surroundings of the Sagan Memorial Station.