On March 29, 1807, the German astronomer Heinrich Wilhelm Olbersobservó Vesta as a point of light in the sky.
Two hundred years later, when NASA's Dawn spacecraft is preparing to go into orbit around this intriguing world, scientists already know how special
this world, but has been some debate about how to classify it. Vesta is commonly called an asteroid because it is in the orbit of a debris region called the asteroid belt located between Mars and Jupiter. But the vast majority of main belt objects are lightweight, with sizes of around 100 miles or less, when compared with Vesta, about 530 kilometers in size on average. In fact, many fragments of Vesta driven by collisions with other objects that have been identified in the main belt
. "I think that Vesta should be considered an asteroid," said Tom McCord, a co-investigator working on the Dawn Bear Fight
Institute. "Not only is Vesta much higher, but it is an object that has evolved, unlike most objects called asteroids." The layered structure of Vesta (core, mantle and crust) is the key factor that makes Vesta in something more akin to planets like Earth, Venus and Mars, as the other asteroids, says McCord. As the planets, Vesta had sufficient radioactive material in the vehicle when it was formed, emitting heat that melted the rock layers and allowed more light be shifted outwards.
Scientists call this process 'differentiation n'.
http://www.jpl. nasa.gov / news / news. cfm? release = 2011-100
0 comments:
Post a Comment