Study Sheds New Light on Early Formation of Earth and Mars

A team of scientists have found that terrestrial planets such as the Earth and Mars may have remained molten in their early histories for tens of millions of years, indicating that the planets cooled slower than previously thought and a mechanism to keep the planet interiors warm is required.
These new data reveal that the early histories of the inner planets in the solar system are complex and involve processes no longer observed. Evidence of these processes has been preserved in Mars, while it has been erased in Earth. So Mars is probably the best opportunity to understand how Earth formed.
Scientists think that early crust formation alone cannot account for the slow cooling magma ocean seen in large planets. This new evidence instead implies that Mars, at one time, had a primitive atmosphere that acted as the insulator.

http://www.marstoday.com/news/viewpr.html?pid=24081