DC,<br /><br />Most of the planetary systems of other stars discovered to date seem rather exotic, based against our prior calibration or standard (i.e.: what we all grew up knowing about the one model available, the Solar System). Many of the new exoplanets are multi-jovian mass bodies that are either very close to their parent star or on rather eccentric orbits, or both. To date, there has not been a hit: the discovery of another star system with a “topography” like our own (a Jupiter-like object in a Jupiter-like orbit). <br /><br />You should be happy as this fact has indeed raised more than one eyebrow among astronomers. Right up until 1995 the typical view (based again on that one data point) was that our own Solar System is the logical final product of the evolution of a circumsolar disk of dust. <br /><br />Question is: was everybody wrong, and is our solar system a rare gem? <br /><br />A recent study by astronomers suggests that Jupiter may be a run of the mill massive planet and due to the fact that (at present) all the radial-velocity measurements either do not have the sensitivity or targets haven't observed long enough to detect an exo-Jupiter at approximately 5AU from its parent star on a 12-year-orbit. <br /><br />Things are changing and more data can be good data. There have been quite a few exoplanet discoveries and a crude graph would show a trend for a plot of minimum mass vs. orbital period. As one moves closer to the current detection limit, there is a growing overabundance of exoplanets with low masses and long orbital periods. The researchers extrapolated from that trend and are suggesting that extra-solar worlds with a mass of one Jupiter are perhaps more common than the larger super-jovians.<br /><br />So, wait a few more years and your question may be answered….<br /><br />Clear Skies!<br />--A3K<br /><br />