What Do You Think of Our New Planets? Xena, Charon, and Ceres?

Saturday, March 13th, 2010 at 9:51 am

Here is the link from a few days ago, before yesterday's preliminary vote (which passed Xena, Charon, and Ceres as planets) at the International Astronomical Union (IAU) General Assembly in Prague. However, there is one more vote to go, on the 25th, for the new planets to pass and be called planets.

Incidentally, in the 1800s, Ceres was actually already being called a planet. But when it was later discovered that it was part of the Asteroid Belt, it was demoted to "asteroid." Ceres is bright enough in the sky to be seen with binoculars from Earth.

Basically the IAU is saying that any object in the solar system that is revolving about the Sun and is at least 500 miles in diameter can be called a planet. It also must be round. (Objects start becoming round because of their own gravity pull when they are around 250-500 miles in diameter. But the IAU wants the cutoff diameter to be 500 miles.

However, the problem with making Xena, Charon, and Ceres planets is that there are...
...53 other objects in the Solar System that would qualify as planets, and probably many more to be discovered with the advent of potent telescopes and advanced searching techniques. The list could theoretically grow to over 100 planets.

Charon was Pluto's moon, but since it is nearly the same size as Pluto, and much bigger than the qualifying 500-mile diameter--I think it's something like 1,172 miles in diameter--Charon and Pluto are now being dubbed a double planet. Pluto's diameter is 1,413 miles--just slightly bigger than its "former" moon.
Oops...here's the link:

http://images.google.com/imgres?imgurl=http://www.spaceflightnow.com/news/n0608/16planets/newplanets_100.jpg&imgrefurl=http://www.spaceflightnow.com/news/n0608/16planets/&h=303&w=398&sz=15&hl=en&start=2&tbnid=9xwvUHm4kJQwcM:&tbnh=91&tbnw=120&prev=/images%3Fq%3Dxena%2Bcharon%2Bceres%26svnum%3D10%26hl%3Den%26lr%3D%26client%3Dsafari%26rls%3Den-us%26sa%3DN

By the way, "Xena" is just a nickname for planet 2000 UB>313. Somehow I like Xena better.
Hi Mhiaa,

No, hunny, only Ceres "was" an asteroid. Charon--a pluton--was Pluto's moon, and Xena is another pluton--an icy planet with an elongated, irregular orbit that takes over 200 years to circle the Sun. Charon in Greek mythology is the ferryman that takes people's souls across the river Styx to Hades. Hades of course is the Greek name for Pluto. In Greek myths, Hades was the underworld, while in Roman mythology Pluto is the god of the underworld. So now Pluto and Charon are considered a double planet of plutons rather than one planet and a moon. They are only about 200 miles apart in diameter (1,200 miles to 1,400).
And btw, Xena (2003 UB>313) is for now the farthest planet from the Sun. It is larger than Pluto, I think some 2,200 miles in diameter. I say "for now" because I have the feeling that more and more planets will be "admitted" to our solar system--or just simply discovered.
Hi Answer,

You can call Charon "Charon" {kair'-uhn} (from the Greek) in your language because it's a proper name--He was the ferryman on the river Styx, who transported souls to Hades. You can just call it "The Ferryman" if you want; that's basically what he was, or is.
Hi Splatt, nice list of criteria. Wow, you'd be tough on the panel. Gotta give you props. However, I have a problem with #7: Let's say the Earth were in orbit amidst an asteroid belt--call it the agri-belt--so then we wouldn't be a planet? And how about the fact that all the planets with moons share an approximate orbit around the Sun with other bodies--their moons (despite the fact that they're revolving about their planets, the moons are also in the same approximate orbit about the Sun). I think you have to rethink that one. And regarding your idea that if Charon is a planet, then our Luna and some of the Jovian moons should also be planets: You forget that the reason Charon was taken away from Pluto as a moon was that they are very close in diameter--some 200 miles difference, if I'm not mistaken. Therefore it's a double planet. Sure, Luna's bigger, but Earth is much bigger. Take the analogy of the Major League Baseball divisions in the AL and NL. In the American League East...
...this year (2006), the top two teams there are neck-and-neck (the Red Sox and Yankees). One of them will be the AL East champion, but at the rate they're both winning, it will probably take some 98, 99 wins to be the champ. In the AL Central, the Tigers will probably win the division with some 107 wins. The Chicago White Sox will probably finish second in that division with some 102 wins. In the AL West, the Oakland A's lead the division now with fewer wins than the other division leaders (the Yankees and Tigers), and now that the other AL West clubs have started to fade, it may take only 90 wins to be the AL West Champion. So here's my point: If the Yankees win their division with 98 wins, the Tigers win the Central with 107, and the A's win the West with 92 wins, where will that leave the Chicago White Sox, who won 102, but get no championship because the Tigers won so many games? Of course, they will be in the playoffs as a Wild Card team, because they won the most games...
...out of all three second-place teams in each division, but they cannot have a division championship unto themselves. Likewise, in planetary systems, if someone else is much bigger than you, e.g., Earth compared to the moon, then the Luna loses that division and earth is the "champion." Likewise, for the Jovian system, Jupiter is much bigger than all its moons, so it wins that division hands-down: None of its moons can ever be planets in that "division." So to say that if Charon is a planet, then Luna and some Jovian moons should also be planets, there rilly is no argument there because you're talking about different "divisions." Sure, if Luna were in its own division, say in orbit between Saturn and Jupiter, then indeed it would be "champion of its own division"--i.e., a planet. But it's unfortunate that Luna is playing in the same division as the Oakland A's (Earth), so to speak. (Jupiter would be the Tigers). I will say this: Ganymede would win the Wild Card, if we had one.
Yeah, I just checked...Jupiter's satellite Ganymede is larger in diameter than both Mercury and Pluto. It would definitely have to be a Wild-Card planet! It's the White Sox of Solar System bodies.

(I'd still root for Jupiter in the playoffs! Oh, wait, I'm an A's fan, so I'll have to take Earth in the "AL West.")