The bizarre orbits of minor planets beyond Neptune


Tuesday, January 26 2016 - 12:00 pm, PST
Ann-Marie Madigan
UC Berkeley

The major planets in our solar system are on nearly circular orbits in a well-defined disk plane. The minor planets, however, take very different paths around the sun. Many minor planets are on orbits that tilt 30 degrees or more out of this disk plane; bizarrely, as Dr. Madgian will describe in the talk, they all tilt the same way! Theories for their unusual orbits include the presence of an undetected super-Earth or 'Planet X' at hundreds of AU, or an encounter with a passing star which deposited its own minor planets in our outer solar system.

In this talk, Dr. Madigan will show that these theories are unnecessary, and that it is the gravitational forces between the minor planets themselves that result in their unusual orbital properties. Though individually of low mass, the minor planets together can dictate their own dynamics. This explanation suggests that there is a (tilted and highly-inclined) disk of minor planets, at least two orders of magnitude more massive than the Kuiper Belt awaiting discovery at hundreds of AU. New surveys such as Pan-STARRS and DECam will soon verify/falsify this prediction.

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