M17: Omega Nebula Star Factory
10.12.2002

In the depths of the dark clouds of dust and molecular gas known as M17, stars continue to form. The similarity to the Greek letter capital Omega gives the molecular cloud its popular name, but the nebula is also known as the Swan Nebula, the Horseshoe Nebula, and M17.

Sunspots: Magnetic Depressions
22.03.1998

Our Sun has spots! These spots appear dark in photographs like the one above, but in fact sunspots are quite bright - they are just dark compared to the rest of the Sun. Sunspots are about the size of the Earth and frequently occur in groups, as shown above.

APOD: 2025 April 22 Б Terminator Moon: A Moonscape of Shadows
22.04.2025

What's different about this Moon? It's the terminators. In the featured image, you can't directly see any terminator -- the line that divides the light of day from the dark of night. That's because the featured image is a digital composite of many near-terminator lunar strips over a full Moon.

Sunspots: Magnetic Depressions
13.01.1997

Our Sun has spots! These spots appear dark in photographs like the one above, but in fact sunspots are quite bright - they are just dark compared to the rest of the Sun. Sunspots are about the size of the Earth and frequently occur in groups, as shown above.

Mercury Transits the Sun
13.05.2003

How big is the Sun? The Sun is not only larger than any planet, it is larger than all of the planets put together. The Sun accounts for about 99.9 percent of all the mass in its Solar System.

Saturns Iapetus: Painted Moon
9.08.2009

What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon.

A Cosmic Zoo in Cepheus
17.08.2023

Sprawling emission nebulae IC 1396 and Sh2-129 mix glowing interstellar gas and dark dust clouds in this nearly 12 degree wide field of view toward the northern constellation Cepheus the King. Energized by its central star IC 1396 (left), is hundreds of light-years across and some 3,000 light-years distant.

Unusual Layers on Saturns Moon Phoebe
14.06.2004

What caused the unusual light and dark layers on Saturn's moon Phoebe? The layers were discovered just Friday during the Cassini spacecraft flyby of the small moon. Such layering is particularly evident on the crater just above the image center, where alternating light and dark material makes this crater appear particularly structured.

Saturns Iapetus: Painted Moon
13.01.2012

What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal, while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon.

APOD: 2025 October 4 Б The Rotating Moon
4.10.2025

No one on Earth sees the Moon rotate like this. That's because the Moon is tidally locked in synchronous rotation, showing only one side to denizens of our fair planet. Still, given modern...