To copy part of a reply from another thread.....<br /><br />Well the classic Kuiper belt is from about 30-50 AU. This appears to be the densest area of the leftovers from planetary/solar system formation. We've detected thousands of objects there, none larger than Eris and Pluto. <br /><br />Beyond that are the Scattered Disk Objects, those with a semimajor axis /> 50 AU, with perihelia from about 40-50 AU and aphelia from 60-400 AU. We've discovered about 2 dozen so far. <br />The most extreme is Sedna, ~1500 km across (smaller than Eris and Pluto). It's in an amazing eccentric orbit, with perihelion of ~76 AU, and aphelion of />900 AU! The orbital period is about 11,000 years. Of course we did discover it when it was at it's closest to the sun, but it shows that we have the ability to find objects smaller than the dwarf planets out well beyond the Kuiper belt. <br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>