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

Question

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.")

=)

Answer 1

I think that they need to rethink the definition.

Xena and Pluto should be planets. Charon and Ceres should not.

If Charon is a planet, then Luna and several Jovian and Saturn moons should also be planets.

Ceres is not a planet because, while it is the largest body in the asteroid belt, it does not constitute the vast majority of mass in a similar orbit.

Here are my criteria.

I would say that the following are minimum characteristics of planets. 1 & 2 below are arbitrary, you may prefer other variables.

1. Minimum Mass. 10^20 Kg. (about 1/100th the mass of Pluto).

2. Minimum Diameter. 1,500 Km (about 900 miles)

3. Orbit. Must be in orbit around a sun, and not a planet (therefore, Luna is not a planet, even though it's larger than Pluto).

4. Distance from sun. Not relevant, as long as it is clearly in orbit around the sun. Therefore, a massive sun may have planets dozen's of light-years away.

5. Is not itself a sun. That would be a binary or higher system.

6. Must not be in interstellar space, not associated with a sun or suns.

7 . Not in a field of other bodies with the same approximate orbit. That would leave out anything in the Asteroid Belt and Oort Cloud.

Answer 2

I think whatever choice the IAU makes, there are going to be a number of people unhappy with the decision.
The fact is that in the past 15 years, we have far more idea about our solar system, due to advanced satelites, probes, observational missions, and of course, the Hubble Space Telescope. The technology available to astronomers today dwarves what man had until recently. (How long has it been since we've understood the 'rings' of Saturn'?)
Ultimately there is going to be an arbitrary decision. For now, lets settle on adding these 3 additional planets - I'm guessing with the change in technology expanding at a quantam leap, the IAU will be revising their definition of what a planet is in the not too distant future.

Answer 3

some astrologers already use their transits in charting, even inspite of the undeniable fact that they don't look to be "authentic". I actually have considered Ceres and Charon on astrological charts as planetary our bodies or asteroids for awhile now.

Answer 4

I'll be looking for starlike Ceres with a telescope and star chart printout. It's the only one of the "new" planets that is bright enough to see.

Answer 5

NIce one. What should i call charon in my language. Erm... Oh.. mayge i can call the moon Juwita. Woopsy.. Nice one.. However the Charon is just like the other moons. Rocky place with the spotted meteor shower.

Answer 6

Excellent, and I'm so glad no corporation got their name on them. lol it is like a law firm. I'm just glad Pluto is back (never left in my mind) The more the merrier - most people can't name the other 8 anyhow.

Answer 7

I like Xena, the warrior planet. It's probably full of beautiful warrior princesses up there. Can't wait to hop on a spaceship and visit it.

Answer 8

it's a little unsettling. they have been debating what a planet actually is in committee for quite a while. i think they should have made a few more qualifications, and what exactly defines an asteroid too.

Answer 9

issues 2 consider such as redefining what v've taken for granted as Earth's family... Maybe like all of a sudden ur parents come home with 3 puny kids n tell u these r gonna be ur bros/sis from now... How would u react? :-)

Answer 10

Sorry, I thought it was Chiron. And I thought they were all asteroids, not planets. Guess I'll have to check it out. What do you consider Lilith and Juno, Pallus, etc to be?