[X] My Assistant

[alan]

This abstract http://www.aas.org/publications/baas/v37n3/dps2005/786.htm gives 2003 EL61 mass as 30.2% of Pluto's mass. That gives a center to center separation of 1120 km for a close binary of two equal mass objects. If the bodies had the same density as Pluto they would have diameters of 1280 km. A contact binary might be possible. Once they determine the actual size from the albedo they should be able to better determine its actual shape.

[abalone]

Alan do you know anything about the gravitational deflection one of the Pioneers or Voyagers experienced that may have indicated a distant encounter with a TNO. I seem to remember reading about it some years ago but cant find any reference to it on th net, even Mr. Google is ignorant about it and I am wondering if my memory is failing.

[Bob Shaw]

Alan do you know anything about the gravitational deflection one of the Pioneers or Voyagers experienced that may have indicated a distant encounter with a TNO. I seem to remember reading about it some years ago but cant find any reference to it on th net, even Mr. Google is ignorant about it and I am wondering if my memory is failing.

I hope this question doesn't drift in the direction of 'funny physics'...

[alan]

Is this what you are refering to? (pdf)
http://citebase.eprints.org/cgi-bin/fullte...stro-ph/0503368

[alan]

PIONEER 10 DEFLECTED BY A KUIPER BELT OBJECT? Preliminary results indicate that Pioneer 10 has had an encounter with a Trans-Neptunian object at 56 AU. Using coherent radio Doppler data generated by the Deep Space Network (DSN) at S band frequencies (wavelength ~ 13 cm), PN 10 experienced a gravitational deflection in December 1992. The new body, found by a team at Queen Mary and Westfield College in London, UK, and the Jet Propulsion Laboratory in California, is probably a so-called Kuiper Belt object. If the observations are confirmed by other astronomers, it will be only the second time in history that a Solar System object has been discovered by its gravitational effect alone. The first was the planet Neptune which was discovered in 1846. Its position was predicted because of its gravitational tug on the planet Uranus, which appeared to be behaving oddly following its discovery 59 years earlier.

This story was reported by BBC News Online Science Editor Dr David Whitehouse on 28 September 1999
http://news.bbc.co.uk/1/hi/sci/tech/460095.stm

[abalone]

PIONEER 10 DEFLECTED BY A KUIPER BELT OBJECT?
PN 10 experienced a gravitational deflection in December 1992.
This story was reported by BBC News Online Science Editor Dr David Whitehouse on 28 September 1999
http://news.bbc.co.uk/1/hi/sci/tech/460095.stm

Thank you for the effort Alan.

A few quotes from the article above

"On 8 December, 1992, when Pioneer was 8.4 billion km (5.2 billion miles) away, they saw that it had been deflected from its course for about 25 days."
With Pioneer travelling at 15km/s it would indicate a big object would it not?


Has anything come of this, it happened 13 years ago? Was it ever visually observed from Earth?
"In a few weeks time, they are expected to be able to place an upper limit on the mass of the object and make predictions about its position. Early indications suggest it may be an object that is being ejected from our Solar System after encountering a major planet."

[alan]

Has anything come of this, it happened 13 years ago? Was it ever visually observed from Earth?

How about going to the source? Here is his homepage
http://www.sp.ph.ic.ac.uk/~giacomo/noframes.html

[abalone]

How about going to the source? Here is his homepage
http://www.sp.ph.ic.ac.uk/~giacomo/noframes.html

I have despatched an email, will let you know if anything interesting returns.

[SFJCody]

One Find, Two Astronomers: An Ethical Brawl
http://www.nytimes.com/2005/09/13/science/space/13plan.html

[SFJCody]

Photometric Observations Constraining the Size, Shape, and Albedo
of 2003 EL61, a Rapidly Rotating, Pluto-Sized Object in the Kuiper
Belt


http://arxiv.org/abs/astro-ph/0509401

[alan]

Wow, with three numbers: mass, rotation rate, light curve they were able to significantly constrain the dimensions and density. If its rotation is aligned with the orbit of its satellite it would be ~ 2000 km x 1500 km x 1000 km with a density near 2.6 g/cm^3. That would make it mostly rock, our moon's density is ~ 3.3 g/cm^3.

[SFJCody]

Astronomers reject the term 'planet'

http://www.nature.com/news/2005/050919/full/437456a.html

http://www.space.com/scienceastronomy/0509...definition.html

http://www.timesonline.co.uk/article/0,,11...1791282,00.html
Progress!

[Guest_BruceMoomaw_*]

Maybe -- but also note in the Space.com article:

""Today, a news article in the journal Nature states that the working group has come up with the adjective-adding solution and may forward the final proposal to the IAU Executive Committee within two weeks.

"If that's to be the case, then the group's chairman, Iwan Williams of Queen Mary, University of London, will likely have to act without consensus. 'Every time we think some of us are reaching a consensus, then somebody says something to show very clearly that we're not,' said Brian Marsden, a member of the group and leader of the Minor Planet Center where newfound objects are catalogued.

"Today Marsden told SPACE.com that it's not clear if a consensus will be reached soon. 'I thought maybe we were close,' he said, 'but just yesterday somebody [in the group] insisted we define planet.' That's the very effort that's gone mostly in circles for many months, however."

_________________________________________

This is bearing more and more of a resemblance to that 30-year debate they had in Laputa over how long to boil a 3-minute egg.

[Guest_BruceMoomaw_*]

Meanwhile, the fight over credit for the Planet 10 discovery has just gotten substantially nastier:

http://www.newscientistspace.com/article/d...f-web-data.html

[Guest_RGClark_*]

Meanwhile, the fight over credit for the Planet 10 discovery has just gotten substantially nastier:

http://www.newscientistspace.com/article/d...f-web-data.html

Which Yahoo groups mailing list is that?


Bob C.