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Log, Jul 22, 2005

20+ people.

There is real excitement in the solar system astronomy community - in fact nothing this exciting has happened since 1930 when Clyde Tombaugh discovered Pluto. The solar system has a NEW PLANET with the temporary (and may I say very ugly) name 2003-UB313. Until its discoverers name it and confirm the name with the IAU, I'll call it Planet X.

The credit for this discovery is shared by Mike Brown, Chad Trujillo and David Rabinowitz using the 48" Samuel Oschin telescope. The image you see is by them at the Oschin Telescope. So far, no telescope has been able to resolve the planet as a disk. Planet X is 19th magnitude, making it the only planet too dim to be viewed at FDO. It is 97 AU away from the Sun (Pluto is 39.3 AU away). Its year is 560 years long (compared to Pluto's 246.4 years). The planet is considerably larger than Pluto with a diameter which is approximately 1.5 as large. If Pluto is a planet then Planet X must be one by the same reasoning.

You might wonder why no one has seen the object before. Well first of all, it is very far out and the Sun isn't so much the familiar solar disk, as just the brightest star in Planet X's sky. This makes Planet X very dim. Secondly, Planet X is nowhere close to the orbits of the other planets - it is tilted 44 degrees to the plane of the Ecliptic that contains the orbits of the major planets.

This will really put the cat among the pigeons as far as whether Pluto, Planet X and other plutinos out there really deserve the name. Several other plutinos are almost as large as Pluto including Pluto's own moon, Chiron. I really think that we will resolve the classification the way we did when Ceres was discovered. Initially Ceres was called a planet but as other objects orbiting between Mars and Jupiter was discovered, Ceres lost its claim to being a planet and became instead the largest of the asteroids. This is really the same sort of thing - a belt of objects surrounding the Sun. They extend from the orbit of Neptune to the outer reaches of the Oort Cloud (about half way to the nearest star). We may very well find other plutinos.

Well back to more earthly pursuits. We had an ok night. There were clouds but we could always see something. We viewed Venus, Jupiter and its Galilean Moons, Albireo and M3. We didn't get to more partially due to clouds and partially due to the large crowd. Only 20 people or so signed up, but the lines rarely were that short.

-Les Coleman

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Jul 22, 2005
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Leslie Coleman's Log
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