Kuiper Belt 1930 – Leonard mentions possibility of trans-Plutonian objects 1943 – Kenneth Edgeworth postulates objects beyond Pluto 1951 – Gerard Kuiper predicts that a massive Pluto would disperse small objects into a belt 1980 – Fernandez predicts ‘comet belt’ that resembles what was eventually found
Kuiper Belt Objects 1992 – Jewitt & Luu find QB1 Distance of 42 AU First (third?) object discovered in the Kuiper Belt
More and more KBOs Large searches for KBOs ensued Hundreds discovered within a decade Over 1200 discovered so far Over 70,000 predicted diameters > 100 km orbits 30-50 AU
Pluto Defenders Pluto is different from the KBOs Pluto is bigger than the KBOs Pluto has a moon, Charon Wrong!
Pluto/Charon orbits within Kuiper Belt
KBO Size Comparison
Sidebar: Is the Moon a Moon? Earth Moon
Binary KBOs About 10% of KBOs are binaries
Eris & Dysnomia (2003 UB313)
Easterbunny Eris & Dysnomia Santa & Rudolph
Pluto vs the Kuiper Belt Orbit similar to KBOs Size similar to KBOs KBO companions common Composition similar to KBOs
Pluto vs the Kuiper Belt Orbit similar to KBOs Size similar to KBOs KBO companions common Composition similar to KBOs Pluto has found its family!!
IAU Definition – August 2006 IAU defines “planet” Orbits the Sun Upper mass limit not massive enough to produce fusion Deuterium fusion occurs at about 15x Jupiter’s mass Lower mass limit Massive enough for gravity to make it spherical About 500 miles in diameter Dominates its orbit Dwarf planets meet 1, 2, 3, but not 4
Other Planetary Systems? Solar system alone is category of one ???
We Are Not Alone Lots of dust disks found Proplyds – proto-planetary disks Kuiper Belt sized and larger Some substructure seen
Planets around Other Stars Cannot see directly (yet) Detect via gravitational pull on star Wobble Periodic shift of spectral lines Monitor for many years (several orbits) Giant planets detectable
Planets around Other Stars Current count (May 2006) 162 planetary systems 188 planets 19 multiple planet systems At least 15% of sun-like stars have planets