Saturn's Cleanest Moon: Enceladus
24.11.1995

Enceladus orbits Saturn between the smaller Mimas and the larger Tethys. Enceladus is composed mostly of water ice and has the cleanest and purest ice surface in the Solar System. It's surface therefore appears nearly white. The surface also has many unusual groves and relatively few craters, like Jupiter's moon Ganymede.

An Active Prominence on the Sun
17.06.2018

Sometimes the Sun's surface becomes a whirlwind of activity. Pictured is a time-lapse video of the Sun's surface taken over a two hour period in early May, run both forwards and backwards. The Sun's surface was blocked out so that details over the edge could be imaged in greater detail.

Callisto Full Face
19.01.2002

Callisto's surface shows its age. While probably formed at the same time as Io, the difference between the surfaces of these two moons of Jupiter could hardly be greater. Io's surface is young, shows practically no impact craters, and is continually being repaved by the lava exploding from its many large volcanoes

3D Bennu
17.10.2025

Put on your red/blue glasses and float next to asteroid 101955 Bennu. Shaped like a spinning toy top with boulders littering its rough surface, the tiny Solar System world is about one Empire State Building (less than 500 meters) across.

Mercury's Faults
20.01.1996

The surface of the planet Mercury is not without fault. In this case, however, "fault" refers to unusual surface features that are the topic of much speculation. The above fault line is called Santa Maria Rupes, and runs through many prominent craters.

A Martian River Bed
4.02.1998

This canyon on the surface of Mars appears to have been carved by flowing water. Known as Nanedi Vallis, the terraces and channels visible within the canyon strongly suggest that a river of water once ran here.

APOD: 2025 October 19 Б Comet Churyumov Gerasimenko Creates Its Tails
18.10.2025

Where do comet tails come from? There are usually no obvious places on the nuclei of comets from which the jets that create comet tails emanate. One of the best images of emerging jets...

A Great White Spot on Rhea
30.05.2005

Why caused this great white spot on the surface of Saturn's moon Rhea? The spot was first noticed last year by the robot Cassini spacecraft now orbiting Saturn. Cassini's flyby of Rhea in April imaged in the spot in great detail.

Philae Attempts Comet Nucleus Landing
11.11.2014

Today humanity will make its first attempt to land a probe on the nucleus of a comet. As the day progresses, the Philae (fee-LAY) lander will separate from the Rosetta spacecraft and head down...

Mercury's Caloris Basin
19.01.1996

Mercury, the closest planet to the Sun, has a surface with so many craters it resembles the Earth's Moon. The largest surface feature on Mercury is the Caloris Basin, which resulted from a collision with an asteroid.