GRAIL, set for launch in 2011, will measure gravity and map the moon's gravity. It consists of two satellites that'll orbit the moon for about 90 days, like a pair of mini-moons of the moon.

This object called SDSSJ0946+1006 is the first-ever double 'Einstein ring.' It looks like a double ring around a bright center. There are thought to be three objects here - a distant galaxy that warps the light of two more galaxies exactly aligned behind it.

HD 74156 is a distant planetary system that seemed to have a large gap between two known planets. Astronomer Rory Barnes predicted a planet there and thus become the first to find a planet outside our solar system by predicting its location in advance. That hasn't happened since astronomers found Neptune in our own solar system in the year 1846.

How does a ring-shaped galaxy form? It might result from an impact with another galaxy slamming into its center. Read more about ring galaxies.

NASA scientists have taken close-up images from space of what they're calling 'spiders' on the planet Mars. These spiders aren't life forms, but spidery-looking channels, carved in ice at the south pole of Mars.

Astronomers estimate the total luminosity of the central dozen or so light-years of the Milky Way to be equal to about 10 million suns. But the center of our galaxy is 27,000 light-years away.

Betelgeuse - the somber red star in the shoulder of the constellation Orion the Hunter - is one of the largest stars visible to the eye alone. Massive stars like Betelgeuse will eventually explode as supernovae. Astronomer Brad Schaefer told Earth & Sky that Betelgeuse could become a supernova any day now.

In 2007, scientists took a step forward in finding evidence for former life on Mars. A rock split open by the wheels of the Mars Spirit rover revealed that it, and rocks surrounding it, were made of more than 90 percent silica. These silica-rich rocks might be deposits from former hot springs on Mars, similar to hot springs found at Yellowstone National Park.

In 2007, astronomers discovered Gliese 581c, a planet whose radius is 50% larger than that of our Earth. Using computers to investigate the properties of distant worlds like this one, these scientists believe that plate tectonics - shifting land plates - might be possible. That's significant because plate tectonics on Earth drive a key mechanism for earthly life.

Evidence from the Voyager spacecraft reveals that the shape of our solar system is 'squashed.' Ed Stone, Chief Scientist of the Voyager Mission, told EarthSky that the sun creates a bubble around itself. He said that in August of 2007, Voyager 2 reached the edge of the bubble about a billion miles closer to the sun than Voyager 1 did in 2004.