Moon: Light Side or Dark?
October 30, 2012

Research Explains Differences Of Dark And Light Side Of Moon

Lee Rannals for — Your Universe Online

Researchers are saying the massive dark spot seen on the moon, known as the Ocean of Storms, is a scar from a giant cosmic impact.

The team of Japanese scientists says the giant cosmic impact created a magma sea more than a thousand miles wide and several hundred miles deep.

The findings may be able to help explain why the moon's near and far sides are so different from one another. The side of the moon that faces Earth has many flat and dark regions, while the far side has higher elevations and a thicker crust.

Scientists at the National Institute of Advanced Industrial Science and Technology said the flattened 1,800-mile wide section of the moon is just what remains of the impact crater.

The team analyzed light reflection data recorded by Kaguya at 70 million locations across the moon's surface.

They studied the distribution of minerals in mapping data obtained by the Japanese moon exploration orbiters, according to a report by The Asahi Shimbun.

One of the minerals found is the low-calcium pyroxene, which was most likely generated when rock melted under the heat of an impact and concentrated in a near-circle around the Procellarum basin.

The scientists believe an asteroid more than 180 miles in diameter hit the moon about 3.9 billion years ago, leaving a crater and melting much of the moon's rock under the energy of the impact.

They said smaller asteroids shifted the topography further, making it difficult to determine whether the basin is what remains of a major impact.

"The latest study explains why the moon's two sides are so different," Junichi Watanabe, a professor of astronomy at the National Astronomical Observatory of Japan, told Asahi Shimbun. "It helps unravel the mystery of the moon's history."

The latest research was published in the British scientific journal Nature Geoscience.