InterChange Newsletter



Jumpin' Jupiter!
Geoff Lenters, Physics Department, GVSU

The basic model of solar system formation has been around for a while -- The sun and planets formed out of a disk of gas and dust with the denser, heavier materials "sinking" towards the Sun and forming the terrestrial inner planets while the lighter elements such as hydrogen and helium formed the Jovian outer planets. It was both temperature and gravity driven. Case closed, sort of. The details of this process have recently come to light with the detection of a host of other planetary systems in our galaxy beginning in the mid-90s. These other planetary systems have challenged solar system modeling ever since, because these other solar systems are very much different than our own and in general hostile to the formation of life.

David Nesvorny from the Southwest Research Institute in San Antonio, Texas has recently completed a study in which he proposes a new detail into the simulation of solar system formation -- a "jumping-Jupiter". Previously, models suggested a slow inward migration of Jupiter, but the problem with this is that as Jupiter slowly migrates inward, it strongly interacts with the inner terrestrial planets in the simulations, disrupting their orbits and possibly causing collisions among the inner planets. The new "jumping-Jupiter" theory suggests that Jupiter scattered off a 5th gas giant planet which used to be a part of our solar system. This 5th planet was then ejected from the solar system allowing Jupiter to "jump" to near its present orbit.

As always, we must be cautious about our simulation results. Others have pointed out that the current ideas behind the formation of our Moon point to a massive Mars-sized impact on planet Earth which ejected the material that formed our Moon. In this scenario, Jupiter wouldn't need to jump, but could possibly have disturbed the inner solar system in its slow inward migration to cause this collision. Whatever the case may be, our home solar system remains a rare phenomenon among the close to 500 systems discovered outside our own. In addition the field of solar system formation studies is a hot bed of activity!

If you are interested in finding out more, http://exoplanets.org and http://planetquest.jpl.nasa.gov, are good places to start your internet search.  Happy planet hunting!