The Once and Future Moon
Smithsonian Air & Space
A recent discovery from the Spitzer Space Telescope may yield new insight into the origin of our own Moon. Although this discovery was in the news some time ago, the advent of the Augustine report and the LCROSS mission results have eclipsed it.
The Spitzer Telescope found evidence for a planetary collision around the star HD 172555, about 100 light-years away from our Solar System. This evidence was a heat signature associated with spectral evidence for silicon monoxide gas (a fairly rare substance) and glassy silica dioxide, a common form of silica glass found associated with volcanoes on Earth. These substances were found associated with a large cloud of silicate debris: the ground-up and pulverized parts of the outer portions of two rocky planets. The evidence suggests that two planets collided with each other at relative speeds exceeding 10 kilometers per second.This set of circumstances is (more or less) the same that we expect in the aftermath of the currently favored model for the origin of our own Moon.