The Moon is
the Earth's only natural satellite. Though its mass is only 1/81
that of the Earth, the Moon is an unusually large satellite in terms
of relative size. As a planet,the Moon is a primitive body on which
the very earliest stages of crustal evolution (more than 4 billion
years ago) are preserved. Its surface environment is clue to that
of space itself.There is no atmosphere at all, and no global magnetic
field, although there are local magnetic anomalies.The surface is
like damp beach sand consisting of rock fragments produced by billions
of years of meteoritic bombardment.The Moon is a fascinating body
to study, and a potentially valuable site for astronomical observatories
on its surface.
No matter how
the Moon formed, its creation must have had dramatic effects on
Earth. Although most scientist have concluded that the Moon formed
as a result of an enormous impact on Earth, we do not know much
about the details of that event. We do not know if the Moon was
made mostly from Earth materials or mostly projectile; the kinds
of chemical reactions that would have taken place in the melt vapor
cloud; and precisely how the Moon was assembled from this cloud.
VIDEO OF PAUL LOWMAN
Paul D. Lowman,
Jr. is a geologist with the Geodynamics Branch of the GSFC Laboratory
for Terrestrial Physics, and has been with the Center since 1959.
In a 40 year career, he has worked on the Mercury, Apollo, and Skylab
programs. His research includes comparative planetology, global
tectonics, and remote sensing. His current project is a book for
Cambridge University Press, "Exploring Earth: the Impact of
Space Flight on Geology and Geophysics."
of the Moon's Copernicus crater.
of Earth from the Moon during the Apollo 11 Mission.