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[Chicago Astronomer - Astro Joe]

Kuiper Belt Moons Are Starting to Seem Typical

In the not-too-distant past, the planet Pluto was thought to be an odd bird in the outer reaches of the solar system because it has a moon, Charon, that was formed much like Earth's own moon was formed. But Pluto is getting a lot of company these days. Of the four largest objects in the Kuiper belt, three have one or more moons.

"We're now beginning to realize that Pluto is one of a small family of similar objects, nearly all of which have moons in orbit around them," says Antonin Bouchez, a California Institute of Technology astronomer. Bouchez discussed his work on the Kuiper belt Tuesday, January 10, at the winter meeting of the American Astronomical Society (AAS).

As for the other Kuiper belt objects, experts at first thought that the bodies acquired their moons only occasionally by snagging them through gravitational capture. For the smaller bodies, the 11 percent figure would be about right.

But the bigger bodies are another story. The biggest of all-and still awaiting designation as the tenth planet-is currently nicknamed "Xena." Discovered by Caltech's Professor of Planetary Science Mike Brown and his associates, Chad Trujillo of the Gemini Observatory and David Rabinowitz of Yale University, Xena is 25 percent larger than Pluto and is known to have at least one moon.

The second-largest Kuiper belt object is Pluto, which has three moons and counting. The third-largest is nicknamed "Santa" because of the time of its discovery by the Mike Brown team, and is known to have two moons.

"Santa is an odd one," says Bouchez. "You normally would expect moons to form in the same plane because they would have accreted from a disk of material in orbit around the main body.

"But Santa's moons are 40 degrees apart. We can't explain it yet."

The fourth-largest Kuiper belt object is nicknamed "Easterbunny"-again, because of the time the Brown team discovered it-and is not yet known to have a moon. But in April, Bouchez and Brown will again be looking at Easterbunny with the adaptive-optics rig on one of the 10-meter Keck telescopes, and a moon might very well turn up.

More here: www.physorg.com/news9796.html

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It must be troubling to the steadfast mainstream conformist in that their view of cosmology is changing daily.

It's a different Universe today, I'm glad...

[Maddad]

It's only the common man who's view is changing. Astronomers have known for a long time that the Kuiper Belt probably housed objects bigger than Pluto.

The statement that Xena is 25% larger than Pluto is based on the assumption that it reflects the same amount of light for its size that Pluto does at the same distance. There was no reason for the assumption other than we didn't have a reason to suppose otherwise. Since then we've gotten some better information, objects orbiting Xena, that allow us to use Keplarian math to calculate its mass, and therefore its size, more accurately. We now think its mass is more like 32% that of Pluto, instead of slightly more. That's what I remember from a story I read a month or so ago anyway. I'd have to look it up to be sure.