Martian Moon Phobos from MGS
1.07.2003

Why is Phobos so dark? Phobos, the largest and innermost of two Martian moons, is the darkest moon in the entire Solar System. Its unusual orbit and color indicate that it may be a captured asteroid composed of a mixture of ice and dark rock.

M57: The Ring Nebula
4.05.1998

It looked like a ring on the sky. Hundreds of years ago astronomers noticed a nebula with a most unusual shape. Now known as M57 or NGC 6720, the gas cloud became popularly known as the Ring Nebula.

The N44 Superbubble
6.02.2006

What created this gigantic hole? The vast emission nebula N44 in our neighboring galaxy the Large Magellanic Cloud has a large, 250 light-year hole and astronomers are trying to figure out why. One possibility is particle winds expelled by massive stars in the bubble's interior that are pushing out the glowing gas.

Europa Rising
7.05.2007

When passing Jupiter on your way to Pluto, what should you look for? NASA pondered just this question recently, and the response from one space enthusiast was to capture the above breathtaking moonrise.

Galaxies Collide in NGC 3256
6.05.2008

Galaxies don't normally look like this. NGC 3256 actually shows a current picture of two galaxies that are slowly colliding. Quite possibly, in hundreds of millions of years, only one galaxy will remain.

Fata Morgana: A Possibly Titanic Mirage
15.04.2012

Did this mirage help sink the Titanic? The optical phenomenon called Fata Morgana can make strange shapes or a false wall of water appear above a watery horizon. When conditions are right, light reflecting...

A Filament Across the Sun
20.08.2012

Is that a cloud hovering over the Sun? Yes, but it is quite different than a cloud hovering over the Earth. The long light feature on the left of the above color-inverted image is actually a solar filament and is composed of mostly charged hydrogen gas held aloft by the Sun's looping magnetic field.

Wringing a Wet Towel in Orbit
24.04.2013

What happens if you wring out a wet towel while floating in space? The water shouldn't fall toward the floor because while orbiting the Earth, free falling objects will appear to float. But will the water fly out from the towel, or what? The answer may surprise you.

Flowing Auroras Over Norway
9.06.2013

Have you ever seen an aurora? Auroras are occurring again with increasing frequency. With the Sun peaking at its eleven year maximum in aurora-triggering activity, it is exhibiting a greater abundance of sunspots, flares, and coronal mass ejections.

A Mercury Transit Sequence
4.05.2016

This coming Monday, Mercury will cross the face of the Sun, as seen from Earth. Called a transit, the last time this happened was in 2006. Because the plane of Mercury's orbit is not exactly coincident with the plane of Earth's orbit, Mercury usually appears to pass over or under the Sun.