Big Tno Discovery Options

[SFJCody]

http://pluto.jhuapl.edu/overview/piPerspec..._09_2005_2.html

[SFJCody]

From the September issue of Physics World [article not online]

Marsden relents on the re-classification of Pluto.

"...current culture dictates that there are nine planets - Mercury to Pluto - the ninth one being there for better or for worse."
However, in his opinion, the new body is not a planet as it has no cultural history beyond the last few weeks.

Also:

The IAU hopes to announce the decision of its working group within the next few weeks.

[Guest_BruceMoomaw_*]

Dear God, I hope they're not going to follow through on that halfwitted idea. Of all their possible courses of action, that is the ONLY one that is unacceptable and indefensible.

[David]

Dear God, I hope they're not going to follow through on that halfwitted idea.  Of all their possible courses of action, that is the ONLY one that is unacceptable and indefensible.

Maybe if that happens the astronomical community will simply rebel against the diktat of the IAU. Then they can just do whatever they like, which of course is what they were doing for centuries before the IAU came around.

[SFJCody]

Maybe if that happens the astronomical community will simply rebel against the diktat of the IAU.    Then they can just do whatever they like, which of course is what they were doing for centuries before the IAU came around.

The IAU group seems to have a fear of making an arbitrary distinction. I'm not sure where this fear comes from. There are lots of arbitrary distinctions in science and they harm no-one. The dividing line between a G class star and a K class star in stellar astronomy is a temperature of 5000K. The dividing line between sand and silt in sedimentary geology is a grain size of 62.5 µm. Why is it unscientific to do something similar for planetary bodies?

[Rob Pinnegar]

There are lots of arbitrary distinctions in science and they harm no-one. The dividing line between a G class star and a K class star in stellar astronomy is a temp of 5000K.

Yeah, when trying to classify bodies in a continuum population, arbitrary distinctions are really unavoidable. In a way, that's kind of the root of the problem: we're now dealing with a continuum population (as far as size is concerned at least) whereas that wasn't the case before.

Before Charon's discovery, the distinction between planet and asteroid was pretty clear. From Mercury to Earth was a 19-fold difference in mass; from Earth to Neptune a 17-fold difference; and from Neptune to Jupiter an 18-fold difference. But from Ceres to Mercury is a 380-fold difference which provided a nice dividing line.

With Charon's discovery, Pluto's mass became known and it dropped neatly into the middle of that nice neat 380-fold difference, being 15 times as massive as Ceres but 25 times less massive than Mercury. The new object UB313 might end up being almost right at the logarithmic "half-way" point. No more neat distinction.

In a way, I can understand the IAU's reluctance to make a decision now. It might really be better for them to just keep stalling. There really isn't any rush -- Pluto and UB313 will still be there in ten years, by which time we will probably have a much better grasp of the size distribution of the bodies in the Kuiper Belt and inner Oort Cloud. At the rate that large KBO's are being discovered these days, there should be a lot more of them known in a few years. Making the decision now will almost guarantee having to either retract it, or heavily modify it, sometime down the road. For the rest of us, it's a frustrating wait, but it might cause less confusion in the long run.

Maybe 2015, New Horizons' arrival at Pluto, would be a good target date for deciding whether Pluto ought to be called a planet. Same goes for UB313 and any other similar objects found between now and then.

[Phil Stooke]

dvandorn said "I guess you could call the "dwarf" varieties something else, like "minor planets" or "planetoids," but I like dwarf better. "

I think they prefer to be called 'diameter-challenged'.

Phil

[hendric]

I think they prefer to be called 'diameter-challenged'.

Phil

Volume constrained!

[SFJCody]

Although there is no mention of any of the three new giant KBOs other than 2003 EL61 (AKA K40506A ) at http://www.aas.org/publications/baas/v37n3...s2005block.html

I have found some information suggesting that new data on 2003 UB313 will be presented on Thursday. Dunno what it'll be though.

[Jyril]

I have found some information suggesting that new data on 2003 UB313 will be presented on Thursday. Dunno what it'll be though.

Results from the new Spitzer observations?

[SFJCody]

Results from the new Spitzer observations?

That or Keck.

[abalone]

Interesting article. What happens to our discussion if they find half dozen Earth sized TNO's in the next few years?

http://www.spacedaily.com/news/kuiper-05e.html

[Decepticon]

I was looking for one of these charts, Thanks to above post!. It shows 2003 UB313 size in relation to Pluto and the moon.





http://skyandtelescope.com/news/article_1560_1.asp

[SFJCody]

http://cfa-www.harvard.edu/iauc/RecentIAUCs.html

Fragment from IAUC 8596:

if the variations are due to rotation, then the period exceeds 8 hr.
However, the observed variation might be due to other effects, such
as unknown color terms.

[ljk4-1]

http://www.centauri-dreams.org/2005.08.28_...l#1125582509708

An Infrared Hunt for Artificial Kuiper Belt Objects

If extraterrestrials were to set up a colony in our Solar System, where would they choose to settle? Gregory Matloff and Anthony R. Martin make the case for the Kuiper Belt in a recent paper for the Journal of the British Interplanetary Society. Kuiper Belt Objects (KBOs) are, after all, easy to exploit as a resource base without the burden of a planet's gravity well. They are rich in volatile materials (more so than main belt asteroids), close enough to the Sun to harvest solar power, and far enough out that visits by those of us living in the inner Solar System would be few and far between.

Moreover, the orbits of KBOs are relatively unaffected by planetary perturbations. Matloff was intrigued enough by these factors to make a proposed infrared search of the Kuiper Belt the subject of a 2004 paper ("A Proposed Infrared Search for Artificial Kuiper Belt Objects," JBIS 57, pp. 283-287). His new paper follows this up with an examination of the characteristics that artificial KBOs ought to display, comparing these to known objects.

How big would such an artificial habitat be? The earlier paper assumed a radius of five kilometers, on the same order of magnitude as some O'Neill designs that would house 10,000 people and more, but the authors of this new study factor in size variations up to 50 kilometers and weigh the effects of varying degrees of reflectivity. Certain assumptions are unavoidable: Matloff and Martin assume, for example, that the temperature of an artificial KBO is within the range 273-373 K, the temperature range of liquid water.

The authors find that the K-band astronomical photometric filter is sensitive to radiation temperature variations in their hypothetical artifical KBO (this is a significant result, for Earth's atmosphere is relatively transparent in this spectral band). They also discuss visible bands of infrared in which artificial objects should be distinguishable from real KBOs. The authors then run their criteria against NASA's Planetary Data System. A small number of real objects have characteristics similar to those predicted for artificial bodies.

This work thus results in an initial selection of targets for an advanced infrared search for artificial objects, using these criteria:

Low mass KBOs are favored, making plutinos primary targets (plutinos are small objects locked, as is Pluto, in an orbital resonance with Neptune).
Stable orbits are favored, making classical objects the next target (these are KBOs with circular orbits but often high inclinations (in excess of 30 degrees).
Highly eccentric orbits offer the least likely candidates.

The authors examine the facilities available for infrared observation, from large ground-based telescopes using adaptive optics (think ESO's Very Large Telescope in Chile, or the twin Keck telescopes on Mauna Kea in Hawaii) to the Hubble Space Telescope, the Infrared Space Observatory and the Spitzer Space Telescope. "The intriguing situation exists that only a few real KBOs have photometric characteristics similar to those predicted for artificial bodies, but infrared observations of KBOs are limited," Matloff and Martin write.

Their paper concludes with a series of suggestions for improving such observational data, including studies in the K-band and coordinated use of Hubble and Spitzer to obtain full infrared data on the targeted KBOs. The paper is Gregory L. Matloff and Anthony R. Martin, "Suggested Targets for an Infrared Search for Artificial Kuiper Belt Objects," JBIS 58 (January/February 2005), pp. 51-61.