Geologists propose theory about a famous asteroid

The asteroid Vesta is the second largest asteroid in our solar system. With a diameter of about 330 miles, it orbits the sun between the planets Mars and Jupiter.

Asteroids have long played a part in building popular fascination with space. “Marooned off Vesta” was the first story published by American writer Isaac Asimov, the third story he wrote, appearing in the March 1939 issue of the science fiction magazine Amazing Stories.

“When we think of asteroid belts, we probably picture Han Solo maneuvering the millennium falcon through a dense set of irregularly shaped gray rocks in space,” Christian Klimczak, associate professor in the Franklin College of Arts and Sciences department of geology. “While most rocks are indeed irregularly shaped and gray, they are far apart and NASA’s Dawn spacecraft did not have to maneuver around any other asteroids to reach and explore Vesta.”

Dawn was the space probe launched by NASA in September 2007 with the mission of studying two of the three known protoplanets of the asteroid belt, Vesta and Ceres.

Vesta, like Earth, is composed of rock in its crust and mantle, and it has an iron core.  Because of its large size (for an asteroid) and because Vesta has a crust, mantle and core, it is considered a planetesimal. Planetesimals are building blocks out of which planets form. Earth formed by accretion of several such planetesimals. “Vesta was on the way to becoming an Earth-like planet, too, but planet formation stopped along the way there early in the history of our solar system,” Klimczak said. “Therefore, studying Vesta helps us understand the very early days of our planetary neighborhood and how our own planet formed.”

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Image of Vest asteroid, courtesy of NASA/JPL