Scientists Stunned by Surface of Asteroid Vesta

The first close-up pictures of the massive asteroid Vesta reveal a northern hemisphere littered with craters -- including a trio nicknamed "Snowman" -- and a smoother southern half, researchers reported Monday.

Running along the asteroid's equator are deep grooves -- a surprise to scientists who did not expect to see such features.

"We're seeing quite a varied surface," said chief scientist Christopher Russell of the University of California, Los Angeles. The images were taken by NASA's Dawn spacecraft, which began orbiting the 330-mile (530-kilometer)-wide rocky body last month and beaming back incredible surface details that the team is only beginning to pore over. It's the first time that Vesta has been viewed up close. Until now, it has only been photographed from afar.

Since entering orbit, Dawn has taken more than 500 pictures, while refining its path and inching ever closer to the surface to get a better view. The probe will officially start collecting science data next week once it is 1,700 miles (2,735 kilometers) from the surface. It will get as close as 110 miles (177 kilometers) while it orbits Vesta for a year.

Vesta's southern section is dominated by a giant crater, the result of a collision eons ago that's believed to have pelted Earth with numerous meteorites, or broken off pieces of asteroids. The northern side is filled with older craters including three that scientists dubbed "Snowman."

Vesta is "so rich in features" that it will keep scientists busy for years, said Holger Sierks, of the Max Planck Society in Germany, who helps operate the camera.

Some 117 million miles (188 million kilometers) from Earth, Vesta is the second-largest resident of the asteroid belt, a zone between Mars and Jupiter filled with hundreds of thousands of space rocks orbiting the sun. The belt formed some 4.5 billion years ago around the same...