The Gegenschein
26.12.2006

If you look carefully enough, you can even see the glow of the Sun in the opposite direction. At night this glow is known as the gegenschein (German for "counter glow"), and can be seen as a faint glow in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles.

Aurora Persei
9.08.2008

Dark skies are favored for viewing meteor showers -- so the best viewing of this year's Perseids will occur in the early morning. While the Perseid meteor shower is scheduled to peak over...

Water Discovered in Moon Shadow
18.11.2009

Why is there water on the Moon? Last month, the LCROSS mission crashed a large impactor into a permanently shadowed crater near the Moon's South Pole. A plume of dust rose that was visible to the satellite, although hard to discern from Earth. The plume is shown above in visible light.

GRO J1655 40: Evidence for a Spinning Black Hole
5.09.2010

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.

Dark Slope Streaks Split on Mars
18.07.2018

What is creating these dark streaks on Mars? No one is sure. Candidates include dust avalanches, evaporating dry ice sleds, and liquid water flows. What is clear is that the streaks occur through light surface dust and expose a deeper dark layer.

The Fornax Cluster of Galaxies
2.11.2023

Named for the southern constellation toward which most of its galaxies can be found, the Fornax Cluster is one of the closest clusters of galaxies. About 62 million light-years away, it's over...

Moonbow with Sailboats
4.07.2001

Have you ever seen a moonbow? Just as rainbows are lit by the Sun, moonbows are lit by the Moon. Since the Sun is so much brighter than the Moon, sunlit rainbows are much brighter and more commonly seen than moonbows. Pictured above is a moonbow stretching over Salt Pond Bay in St.

A Cerro Tololo Sky
9.11.2002

High atop a Chilean mountain lies one of the premier observatories of the southern sky: the Cerro Tololo Inter-American Observatory (CTIO). Pictured above is the dome surrounding one of the site's best known instruments, the 4-meter Blanco Telescope.

M83: The Southern Pinwheel Galaxy from VLT
11.05.2003

M83 is one of the closest and brightest spiral galaxies on the sky. Visible with binoculars in the constellation of Hydra, majestic spiral arms have prompted its nickname as the Southern Pinwheel. Although discovered...

A Complete Aurora
2.04.1997

Aurora frequently make complete rings around a pole of the Earth. This particular "crown", visible in orange near the top of this image, was taken by the orbiting Polar spacecraft about one year ago and released by NASA last month.