Moon in Inverted Colors
8.03.2022

Which moon is this? It's Earth's moon -- but in inverted colors. Here, the pixel values corresponding to light and dark areas have been translated in reverse, or inverted, producing a false-color representation reminiscent of a black and white photographic negative.

The Sea of Tranquillity: 5 Seconds To Impact
30.07.1999

On February 20th, 1965, the Ranger 8 spacecraft crashed into the Moon. Rapidly transmitting a series of pictures to ground controllers, its camera recorded this one at an altitude of about 11 kilometers, 5 seconds before impacting the lunar surface. Two kilometers across, with 4 meter

The Unusual Boulder at Tychos Peak
7.05.2018

Why is there a large boulder near the center of Tycho's peak? Tycho crater on the Moon is one of the easiest features to see, visible even to the unaided eye (inset, lower right). But at the center of Tycho (inset, upper left) is a something unusual -- a 120-meter boulder.

Unusual Mountain Ahuna Mons on Asteroid Ceres
9.10.2017

What created this unusual mountain? Ahuna Mons is the largest mountain on the largest known asteroid in our Solar System, Ceres, which orbits our Sun in the main asteroid belt between Mars and Jupiter. Ahuna Mons, though, is like nothing that humanity has ever seen before.

Unusual Spires Found on Comet Wild 2
22.06.2004

How did unusual spires form on comet Wild 2? Close inspection of images taken of Comet Wild 2 by the passing Stardust spacecraft in January show numerous strange pinnacles as long as 100 meters long jutting off the surface. The pinnacles were unexpected - close-ups of other comets and asteroids show no such features.

Mercury's Faults
21.01.1996

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.

NEAR Mathilde
30.06.1997

Hey Earth, look what I found! On the way to visiting the asteroid 433 Eros in February 1999, the Near Earth Asteroid Rendezvous (NEAR) spacecraft flew right by another asteroid: 253 Mathilde last Friday. Shown above is one picture from the encounter.

APOD: 2026 July 25 Б Tranquility and Serenity
25.07.2026

The Seas of Tranquility and Serenity are calm today. They're calm most every day though, since they are actually lunar maria, ancient lava flows filling in large impact basins on the Moon. Also...

A Year of Assessing Astronomical Hazards
31.12.2002

Could an asteroid destroy civilization on Earth? Mountain-sized space rocks could potentially impact the Earth causing global effects, and perhaps even be mistaken for a nuclear blast of terrestrial origin. Such large impacts are rare but have happened before. Modern telescopes have therefore begun to scan the skies for signs of approaching celestial hazards.

Comet Tempel 1 from Stardust NeXT Spacecraft
16.02.2011

No comet has ever been visited twice before. Therefore, the unprecedented pass of the Stardust-NeXT spacecraft near Comet Tempel 1 earlier this week gave humanity a unique opportunity to see how the nucleus of a comet changes over time.