A NASA spaceship, its engines too weak to power a skateboard, is drawing closer to a never- visited dwarf planet in a quest to learn more about how Earth was formed.
Dawn, a golf-cart-size NASA probe launched seven years ago, is on its way to rendezvous with Ceres, a minor planet as big across as Texas, on March 6. A rocky globe that probably holds a reservoir of ice, Ceres may provide keys to understanding what our own planet was like at the very beginning of its formation.
Once Dawn reaches Ceres, it will be the first spacecraft to visit two celestial bodies on a single voyage, with a mission to study the formation of the solar system.
Until 2012, Dawn had been circling Vesta, an asteroid whose core resembles our planet's and whose surface was so shattered by impacts that the resulting meteorites have found their way to our planet.
"Both Vesta and Ceres are like building blocks of planets," Marc Rayman, the mission's chief engineer, said.
"Studying them may give us insight into the conditions and process that occurred when planets were forming."
While scientists used to consider the solar system to have nine planets, astronomers demoted Pluto in 2006, putting it in a new dwarf planet category, where it's now joined by Ceres and three others.
Ceres was the first minor planet discovered, having been sighted on New Year's Day in 1801, 129 years before Pluto.