Monday, February 20, 2006

A New Planet Has Been Found?

Recently a Kuiper Belt Object named 2005 UB313 has been discovered. It is about 3 times the distance of Pluto from the Sun, but gets closer in about 200 years. It has an orbital period of 556 years or so, and its diameter is about 1800 miles. This makes it bigger than Pluto, so all over the place in the media, headlines about finding a tenth planet have sprouted. But is it, and Pluto for that matter, really a planet?

People had been so expecting and getting excited about a ninth planet at the beginning of the 20th century so that when a large Kuiper Belt object was discovered by Clyde Tombaugh in 1930, it was instantaneously proclaimed a Planet! They thought it was as big as Uranus, and they called it Pluto. Further observations, including occultations that did not take place, showed it to be much smaller, maybe as big as the Earth, no maybe as big as Mars, no maybe big as Mercury; they really did not know for sure. Then Harrington discovered in 1980 that it had a satellite Charon. Now when two bodies are found in orbit around each other, the mass of both can be computed fairly accurately. Astronomers did that, and found that Pluto was only 1500 miles across. The United States is bigger than that. So that put into serious question whether Pluto should be considered a planet. It has a mass of only 13 yottagrams, compared to 5960 yottagrams (or 5.96 xonagrams) for the Earth, 330 yottagrams for Mercury, 148 yottagrams for Ganymede, 89 yottagrams for Io, and 74 yottagrams for our own Moon. Is the Moon a planet? It is on the borderline. And Pluto is much smaller than that.

It instead was the biggest Kuiper Belt object, a group of large objects outside the orbit of Neptune. Many large Kuiper Belt objects have been discovered, including Varuna, 600 miles across, Charon, 600 miles, Quaoar, 900 miles, Sedna, 1100 miles, closing in on the radius of Pluto. But still Pluto was the largest of the Kuiper Belt objects, so some still considered it a planet.

But now they've done it. Pluto is no longer even the biggest Kuiper Belt object. There is one bigger, namely 2005 UB313
The newly discovered object is about 1.5 times wider than Pluto and therefore 4.5 times more massive, probably. And it STILL is not a planet. Not when its mass is only about 58 yottagrams. If we called the new object a planet, then surely we must call the Moon one. So definitely now, Pluto is NOT a planet.

But the media and the IAU are going to call it a planet, since they call Pluto a planet. The problem with this is that eventually there are going to be too many planets - more in the Kuiper Belt than elsewhere. Eventually they will give up on this, just like they did with calling Ceres, Pallas, and so forth planets near the beginning of the 19th century. They will take planet status away from both 2005 UB313 and Pluto. Now the Mars-Jupiter asteroid belt has one member, namely Ceres, that is much bigger than the rest, and the rest go down rather uniformly from there, from Vesta and Pallas on down. I think that Pluto, 2005 UB313, Quaoar, Orcus, and so forth are the Vestas and Pallases of the Kuiper Belt, and The Big One has still yet to be discovered. By analogy with the Mars-Jupiter asteroids, I would estimate that The Big One, when found, will have a mass approaching 1 xonagram (1,000 yottagrams), and be between the Moon and Mars in size. That definitely would be a planet. But I predict only one of these big kahunahs.

In other words, eventually I think the Solar System will be shown to have 9 planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and not Pluto, but Planet X, a Kuiper Belt object approaching Mars in size. I could be wrong. There might be a bunch of equal-sized objects in the Kuiper Belt, with no planets. But the example of Ceres seems to show to me that there is a Big One yet to be discovered.

Another matter is the naming of 2005 UB313. Mike Brown, the discoverer, first said he was gong to call it Lila, after a daughter, then he said he was going to call it Xena, after the female warrior, and it got spread all over the Internet, but not the main news media. But I don't think that will likely be its name. It just doesn't fit. Hercules, Jupiter, Ceres and so forth are deities or superpeople that are thousands of years old. Xena is only 10 years old, the modern creation of Hollywood to provide an ancient female superhero for girls to aspire to. More appropriate would be to name it after a god of some religion, and underworld gods seem to predominate out here in the dank recesses of the outer Solar System.

So I would like to propose this name: Baiame. Baiame is the God of the Australian Aborigines, specifically the God of Death, and a well-known legend involving the Southern Cross features Baiame. I urge the IAU to select this name for the object, and I am hoping that Australian aborigines will support me on this name for this far distant asteroid. As far as being a planet, in my opinion, it is too small, and so is Pluto. Until something bigger is found, the Solar System will be known to have eight planets.

2005/08/02

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