The Big Splat: Or How Our Moon Came to Be - Book Review

Science News, July 5, 2003

DANA MACKENZIE

For 400 years or so, scientists have toiled over the exact origins of Earth's moon. Even once humans set foot there, the mystery was still not solved. Some astrophysicists argued that the moon was ripped from a rapidly spinning Earth or that it came from elsewhere in the solar system and got caught up in Earth's gravity. Others proposed that the moon and Earth were created from the same cosmic gas and dust. Mackenzie reviews these plausible but not provable ideas and others that preceded what most scientists today say: A Mars-sized object (a doomed planet now called Theia) collided with Earth, and the remains of this giant explosion--the Big Splat--coalesced to form the moon. Mackenzie provides historical accounts of scientists, such as Galileo, Isaac Newton, and George Darwin (son of Charles), who paved the way for William Hartmann to formulate and Alastair Cameron to elaborate on the Big Splat theory. Mackenzie gives readers an accessible introduction to the geology and history of our lunar neighbor. Along the way, he answers questions such as: How old is the moon? What caused its craters? Why is it made entirely of rock? Wiley, 2003, 232 p., b&w photos, hardcover, $24.95.