A Double Eclipse of the Sun
21.03.2015

Can the Sun be eclipsed twice at the same time? Last Friday was noteworthy because part of the Earth was treated to a rare total eclipse of the Sun. But also on Friday, from...

Comet Churyumov Gerasimenko in Crescent
28.04.2015

What's happening to Comet 67P/ChuryumovGerasimenko? As the 3-km wide comet moves closer to the Sun, heat causes the nucleus to expel gas and dust. The Rosetta spacecraft arrived at the comet's craggily double nucleus last July and now is co-orbiting the Sun with the giant dark iceberg.

Discovery in Motion
8.07.2006

On July 4th, the space shuttle orbiter Discovery rocketed into space on mission STS-121. Now docked with the International Space Station, Discovery orbits planet Earth at about 27 thousand kilometers per hour.

APOD: 2025 June 14 Б Meteors and Satellite Trails over the Limay River
13.06.2025

What are all those streaks in the sky? A galaxy, many satellite trails, and a few meteors. First, far in the distance, the majestic band of our Milky Way Galaxy runs down the left. Mirroring it on the right are several parallel trails of Earth-orbiting Starlink satellites. Many fainter satellite trails also crisscross the image.

Beefing Up the International Space Station
16.12.2002

The International Space Station (ISS) will be the largest human-made object ever to orbit the Earth. The station is so large that it could not be launched all at once -- it is being built piecemeal with large sections added continually by flights of the Space Shuttle.

A Solar Filament Lifts Off
25.07.2004

Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above, which was captured in 2000 July by the Earth-orbiting TRACE satellite. The filament, although small compared...

Rotating Asteroid Bennu from OSIRIS REx
12.11.2018

Could this close-by asteroid ever hit the Earth? Eventually yes -- but probably not for a very long time, even though the asteroid is expected to pass inside the orbit of the Moon next century.

APOD: 2026 May 6 Б The Retrograde Dance of Saturn and Neptune
5.05.2026

What does it mean for Saturn and Neptune to be in retrograde? Featured is a composite of images taken over 34 nights from May 2025 to February 2026 tracing Saturn (brighter, foreground) and Neptune (dimmer, background). Over that time, the two planets exhibited retrograde motion, meaning they appeared to move backward in the sky.

Hale-Bopp Brightest Comet This Decade
12.03.1997

The Great Comet of 1997 is now brighter than the Great Comet of 1996 ever was. In fact, it is brighter than almost every star in the sky. Yet Comet Hale-Bopp is still about two weeks away from maximum light.

Lunation
17.02.2001

Our Moon's appearance changes nightly. This slow-loading time-lapse sequence shows what our Moon looks like during a lunation, a complete lunar cycle. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The Moon always keeps the same face toward the Earth.