Phoebe: Comet Moon of Saturn
30.06.2004

Was Saturn's moon Phoebe once a comet? Images from the robotic Cassini spacecraft taken two weeks ago when entering the neighborhood of Saturn indicate that Phoebe may have originated in the outer Solar System.

The Millennium that Defines Universe
1.01.2000

Welcome to the millennial year at the threshold of millennium three. During millennium two, humanity continually redefined its concept of "Universe": first as spheres centered on the Earth, in mid-millennium as the Solar System, a few centuries ago as the Galaxy, and within the last century as the matter emanating from the Big Bang.

Mercury and Jupiter at Sunset
18.03.2011

When warm sunset hues begin to fade, two celestial beacons now shine in the evening twilight, Mercury and Jupiter. Wandering away from the Sun in planet Earth's sky, Mercury will offer good views this month as spring approaches in the northern hemisphere where the ecliptic plane makes a steep angle with the western horizon.

The Altiplano Night
7.07.2016

The Milky Way is massively bright on this cold, clear, altiplano night. At 4,500 meters its reflection in a river, a volcanic peak on the distant horizon, is captured in this stitched panorama under naturally dark skies of the northern Chilean highlands near San Pedro de Atacama.

Conjunction after Sunset
19.12.2020

How close will Jupiter and Saturn be at their Great Conjunction? Consider this beautiful triple conjunction of Moon, Jupiter and Saturn captured through clouds in the wintry twilight. The telephoto view looks toward the western horizon and the Alborz Mountains in Iran after sunset on December 17.

APOD: 2024 December 15 Б Geminid Meteors over a Snowy Forest
15.12.2024

Meteors have been flowing out from the constellation Gemini. This was expected, as mid-December is the time of the Geminid Meteor Shower. Pictured here, over two dozen meteors were caught in successively added exposures taken over several hours early Saturday morning from a snowy forest in Poland.

Io in True Color
20.09.1999

The strangest moon in the Solar System is bright yellow. This recently released picture, showing Io's true colors, was taken in July by the Galileo spacecraft currently orbiting Jupiter. Io's colors derive from sulfur and molten silicate rock. The unusual surface of Io is kept very young by its system of active volcanoes.

Dark Craters on Ganymede
22.07.1998

Ganymede has craters within craters within craters. The old surface of the largest moon in the Solar System shows its age by the large amount of these impact features. The above picture released last...

Cassini Images The Moon
10.09.1999

On August 18, the Cassini spacecraft flew by the Earth and Moon, then continued on its way to the outer solar system. Near its closest approach to the Moon, a distance of about 377,000 kilometers, controllers tested Cassini's imaging systems on this most familiar celestial body.

Nearby Star Epsilon Eridani Has a Planet
7.08.2000

A planet has been found orbiting a Sun-like star only 10 light-years away. No direct picture of the planet was taken - the planet was discovered by the gravitational wobble it created on its parent star, Epsilon Eridani. The discovery marks the closest Sun-like star yet found to house an extra-solar planet.