Mimas: Small Moon with a Big Crater
25.04.1999

Mimas is one of the smaller moons of Saturn but shows one of the largest impact craters. In fact, if the impact had been much greater, it would have disrupted the entire satellite. The large crater has been named Herschel after the 1789 discoverer of Mimas, Sir William Herschel.

Oklo: Ancient African Nuclear Reactors
20.02.2005

The remnants of nuclear reactors nearly two billion years old were found in the 1970s in Africa. These reactors are thought to have occurred naturally. No natural reactors exist today, as the relative density of fissile uranium has now decayed below that needed for a sustainable reaction.

Stonehenge: Ancient Monument to the Sun
12.09.1999

Stonehenge consists of large carved stones assembled about 4000 years ago. Long before modern England was established, ancient inhabitants somehow moved 25 ton rocks nearly 20 miles to complete it. From similar constructs...

Mimas: Small Moon with A Big Crater
24.09.1995

Mimas is one of the smaller moons of Saturn but shows one of the largest impact craters! In fact, if the impact had been much greater, it would have disrupted the entire satellite. The large crater has been named Herschel after the 1789 discoverer of Mimas, Sir William Herschel.

Uranus' Moon Ariel: Valley World
3.03.1996

What formed Ariel's valleys? This question presented itself when Voyager 2 passed this satellite of Uranus in January 1986. Speculation includes that heating caused by the ancient tides of Uranus caused moonquakes and massive shifting of the moon's surface.

Mars Pathfinder's Landing Site
24.07.1997

Where is Mars Pathfinder? Follow the arrow in the above picture taken by the Viking Orbiter in 1976. From the surface Mars appears covered with rocks, but from orbit Mars appears covered with craters. However, several familiar features are visible in this photograph.

Uranus' Moon Miranda
24.12.1995

NASA's robot spacecraft Voyager 2 passed the planet Uranus and its moons in 1986. While the cloud tops of Uranus proved to be rather featureless, the surface of Miranda, the innermost of Uranus' large moons, showed several interesting features.

A Martian Sunset
1.08.1997

You've had a hard day rolling past Martian rocks, so now just relax your APXS and enjoy the Martian sunset. The above pictures taken by Mars Pathfinder highlight how clouds vary during the end of a Martian day.

Pluto: The Frozen Planet
18.08.1995

The Hubble Space Telescope imaged Pluto and its moon Charon in 1994. Pluto is usually the most distant planet from the Sun but because of its elliptic orbit Pluto crossed inside of Neptune's orbit in 1979 and will cross back out again in 1999.

APOD: 2024 July 29 Б Milky Way over Uluru
29.07.2024

What's happening above Uluru? A United Nations World Heritage Site, Uluru is an extraordinary 350-meter high mountain in central Australia that rises sharply from nearly flat surroundings. Composed of sandstone, Uluru has slowly formed over the past 300 million years as softer rock eroded away.