Sylvia, Romulus and Remus
18.08.2005

Discovered in 1866, main belt asteroid 87 Sylvia lies 3.5 AU from the Sun, between the orbits of Mars and Jupiter. Also shown in recent years to be one in a growing list...

MESSENGER s Last Day on Mercury
30.04.2015

The first to orbit Mercury, the MESSENGER spacecraft came to rest on this region of Mercury's surface yesterday. Constructed from MESSENGER image and laser altimeter data, the scene looks north over the northeastern rim of the broad, lava filled Shakespeare basin.

Jupiter, Io, and Shadow
25.12.2000

Just as planets orbit our Sun, Jupiter's Moons orbit Jupiter. Pictured above is the closest of Jupiter's Galilean Satellites, Io, superposed in front of the giant planet it circles. To the left of Io is a dark spot that is its own shadow.

Mare Orientale
11.01.1996

Looking like a target ring bull's-eye, the Mare Orientale is one of the most striking large scale lunar features. Located on the Moon's extreme western edge, this impact basin is unfortunately difficult to see from an earthbound perspective.

Eclipse and Ecliptic
8.03.2007

When a Full Moon lies near the ecliptic there can be a lunar eclipse. That cosmic alignment is well illustrated in this composite of eclipse images recorded last Saturday near Paris, France. The projection...

Perigee s Full Moon
22.06.2013

A big, bright, beautiful Full Moon will rise at sunset on Sunday. Its exact full phase (June 23, 11:32 UT) will occur shortly before it reaches perigee, the closest point to Earth in the Moon's orbit, and make it the largest Full Moon of 2013. But such circumstances are not very rare.

Other Worlds and HD 38529
10.08.2000

After the latest round of discovery announcements, the list of known worlds of distant suns has grown to 50. While extrasolar planet discoveries are sure to continue, none - so far - points clearly to another planetary system like our own. Take, for example, the newly discovered parent star HD38529.

The Largest Rock Known
1.01.2000

There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid, moon, and comet nucleus. It is larger than any other rocky planet. (Nobody knows...

Millions of Stars in Omega Centauri
16.04.2002

Pictured above is the largest ball of stars in our Galaxy. About 10 million stars orbit the center of this globular cluster - named Omega Centauri - as this giant globular cluster orbits our Galactic center.

APOD: 2025 June 21 Б Two Worlds, Two Analemmas
20.06.2025

Sure, that figure-8 shaped curve you get when you mark the position of the Sun in Earth's sky at the same time each day over one year is called an analemma.