Theorist on Creation of Moon Dies

Alastair G. W. Cameron, a Harvard astrophysicist who helped develop a revolutionary theory to explain how the Moon was formed, died Oct. 3 at his home in Tucson. He was 80.

Dr. Cameron's famous work, known as the giant impact theory, holds that a planet roughly the size of Mars struck Earth, sending fragments of Earth's mantle spinning into the atmosphere. The ring of space debris that resulted may have ultimately come together to form the Moon.

Out of respect, tonight the moon will fall from the sky for a moment of silence.