
                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: FRIDAY, May 26, 1995                   TAG: 9505260081
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A-7   EDITION: METRO 
SOURCE: Associated Press|
DATELINE: WASHINGTON                                LENGTH: Medium

IT'S DEFINITELY NOT MADE OF CHEESE

Billions of years ago, the moon became the Earth's only natural satellite after smashing into the planet and bouncing back out into space, according to new evidence supporting an old theory.

Data from a lunar research satellite called Clementine show that the bulk composition of the moon has much less iron than previously believed and that it is far different from the composition of the Earth, said Paul G. Lucey, a University of Hawaii scientist.

``We concluded that the moon did not form from the same source material as the Earth,'' said Lucey. ``The moon is really quite different than the Earth in composition.''

This means, he said, that two of the four major theories about lunar origin are wrong and that only one theory, the ``giant-impact'' hypothesis, is most likely correct.

A report on the study is to be published today in Science, the journal of the American Association for the Advancement of Science.

Graham Ryder, a staff scientist at the Lunar and Planetary Institute in Houston, said the Lucey study gives a big boost to the giant-impact theory of the moon's origin, but that more studies are needed before the theory is accepted as fact.

``The study is really excellent, but it doesn't prove the theory,'' Ryder said. ``But giant impact is the only model we have that fits these data.''

The four major theories for the moon's origin are:

Co-accretion: The moon formed in the same place and of the same materials as Earth.

Fission: The moon is a chunk of Earth that was broken away from the planet and was propelled into orbit by an asteroid impact.

Giant Impact: The moon was a Mars-size rock that hit Earth; a large part, perhaps in the form of molten rock, ricocheted into an orbit about the planet.

Capture: The moon was a huge rock that wandered into Earth's gravitational grasp and was captured in the planet's orbit.

by CNB