Quirks & Quarks

Pulverizing Planets

Our solar system may once have had extra planets that were smashed to smithereens.
Artist's conception of two planets colliding. (NASA/JPL-Caltech)
When they look out at other solar systems, one of the things astronomers notice is that systems with several planets in close to their suns seem quite common.

According to Dr. Kathryn Volk, a post-doctoral fellow in the Department of Physics and Astronomy at the University of British Columbia, this may be a normal outcome of solar system formation. That made her wonder why other solar systems - like ours - don't have extra planets at distances inside the orbit of Mercury.

In new work, Dr. Volk calculated that orbital instabilities in these inner planets can lead to catastrophic and planet-shattering collisions - early in the life of the solar system - that scatter debris throughout the inner solar system. Evidence for this early solar system havoc may still exist in the composition of Mercury and cratering on the Moon.

Related Links

- Paper submitted to Astrophysical Journal Letters
New Scientist story