Moon's abnormal bulge due to past oval orbit

An odd bulge on the moon's surface has been a mystery to astronomers since it was first discovered over 200 years ago, but a new study now shows its origin.

Scientists at the Massachusetts Institute of Technology (MIT) believe that the moon engaged in an "eccentric" oval-shaped orbit 100 million years after its formation.

During this period of elliptical orbit, an excess amount of material formed around the moons equator before the moon's surface even solidified, the scientists say.

In order to study this orbital past, MIT scientists extrapolated backwards from ancient records of solar eclipses, and changes in distance between the Earth and our moon.

As time went on, the scientists say the orbit gradually became more circular and the moon developed into its solid form that we know today.

A French astronomer discovered the bulge in 1799, but this report is the first with substantial evidence of where it came from.

The researchers' findings were published in the August 4 issue of Science.

Photography: Russells Astronomy

Source: Discovery Channel Reports, August 4 edition