spacetoday.net: Mars formed quickly, stunted growth

Posted: Mon, May 30, 2011, 9:02 AM ET (1302 GMT)
Mars seen by Hubble August 2003 (STScI)

The planet Mars may be a "planetary embryo" that formed quickly but failed to develop into a larger terrestrial planet, scientists recently reported. In a paper in the latest edition of Nature, scientists estimated the planet's age by measuring the ratio of various elements found in Martian meteorites that are byproducts of radioactive decay, and applying that data to computer models of the planet's formation. They found that Mars reached half its present size just two million years after the solar system's birth, far faster than previous thought. Scientists argue that Mars may have been one of many "planetary embryos" that formed after the solar system's birth. Many of the other such embryos collided with one another to form larger terrestrial planets like Earth, but Mars may have never been involved with such collisions.