Moon around Kuiper Belt Object

UncleJosh writes "Today's NY Times (free reg rq'd) has a story about the first Kuiper Belt Object (KBO) with a moon, 1998 WW31. The hubble telescope has been used to get information about the size and orbit of the moon. Seems lots of things have moons. Coming more than 20 years after the discovery of Pluto's moon Charon the discovery of a KBO with a moon also follows the discovery of asteroid Ida's moon Dactyl and other moons of asteriods."

Comments

Too bad this isn't in the main section

[ramoth4]

I'd like to see what others think about this, instead of a measly 2 replys.

This poses major questions though, about what exactly is a planet. Is Jupieter a planet? It puts out more heat than it takes in. What about Pluto? It's not in a regular orbit. What about that whole "Nemesis" theory? What's that got to do with this?

Re:Too bad this isn't in the main section

[Cy Guy]

[Pluto]'s the largest (discovered) Kuiper Belt object

Which would therefore make Pluto the first discovered Kuiper Belt object to have a moon, making a total of Eight with the seven referenced in the article.

It was later discovered that it was smaller than originally thought. We still call it a planet today because we've been calling it one all along.

Given that there are other Kuiper Belt objects on the same order of magnitude in diameter as Pluto, and that Kuiper Belt objects with moons seem common, isn't there even greater reason to reclassify Pluto? With a mass of just 4% of the next smallest planet (only 1/8th the most massive moon in the Solar System), why should it continue to be singled out from the other KB objects? Isn't science about taking new information and changing our assumptions and definitions to comform with new facts as they discovered?

Hubble space picture of 1998 WW31

[Anonymous Coward]

Posted on the Hubble site 7 days ago when this was news.

This is not surprising

[n-baxley]

Two boides are attrackted while spinning in orbit around another, larger body. They start to co-orbit. That's physics people. Why do we have to call the smaller of these two objects a moon? These are just two asteroids who are orbiting each other. That's it. Sheesh.

This IS surprising (physics)

[Spamalamadingdong]

Two boides are attrackted while spinning in orbit around another, larger body. They start to co-orbit. That's physics people.

Two bodies approach each other from "infinity", and somehow they lose enough energy and/or angular momentum in their encounter to wind up in mutual orbit. How's that? What's the mechanism for dissipating energy, or transferring angular momentum from motion of the bodies around their center of mass to spin of the bodies themselves (Earth and Luna are doing this in reverse, but very slowly; far too slowly to capture anything).

Since you've set yourself up as the physics expert, perhaps you'd like to explain that to all of us. You'll probably get a publishable paper out of it too, so it's not like it isn't worth the work.