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Friday, July 22, 2011


Now THAT'S the Way to Test a Theory (Yes, Elenin Really is Small)

There has been a lot of angst about the size of comet C/2010 X1 Elenin on the internet, with some people worried it is either a Brown Dwarf Star or the Satellite of a Brown Dwarf. Both Leonid Elenin and I have used maths and simulations to show that the comet must be small, but people continue to be anxious, and are discussing the matter endlessly on various discussion groups.

Except a commenter called Astronut, who did something unthinkable, rather than endlessly nattering he actually tested the hypothesis that Elenin was big.

He bought time on a remote telescope (one of the Slooh scopes) in the Canary Islands, and measured the position of asteroid (74732) 1999 RQ176 twenty -four hours after it's close encounter with comet Elenein on May 20.

And it was exactly where it was predicted to be (see also Leonid Elenins images of the asteroid post encounter).

Now, this pass was very close, at it's closest 1999 RQ176 was 225,830 km from Elenin (around 0.002 AU), which is 0.59 of the average distance between the Earth and Moon. If Elenin was as massive as Jupiter, it would have substantially altered the asteroids location. And I mean substantially, not just a few arc minutes off, more like being degrees off, the asteroid sling-shotted off into deep space.

Actually, if Elenin was a Brown Dwarf, with a radius of 4 times that of Jupiter (285 968 Km), at closest approach the asteroid would have been deep inside the Brown Dwarfs photosphere, and wouldn't have come out again.

The very fact that we could see 1999 RQ176 at all, means that Elenin is not a Brown Dwarf.

Science is at its heart a practical enterprise, we test things, and Astronut has shown that citizen scientists can make significant contributions, all props to you Astronut.

UPDATE: Astronut follows up the observations here.

PS, if Astronut or one of Astronut's friends reads this, could he/she get in contact with me, Global Rent-a-Scope has an offer for you.

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Hi Ian,

If we can contact Astronut directly we would like to offer him a free account for GRAS Use. Can you help?

That is a fantastic idea. I think I can get his contact, I'm off the AVCON for the weekend, so this may not happen until later. (Any folks reading this who DO have contact with astronut, can you email me?)
On May 21st Comet Elenin attacked asteroid 1999 RQ176 and proved it is less massive than Halley's comet.

messierhunter on Youtube (Jul 14, 2011):

NGCHunter from BAUT:
Hello Sir Ian Musgrave!

My name is Edgar Luis Gomez, of Mexico an amateur astronomer. :)

I have a blog dedicated to Comet Elenin, I am providing true information of the comet for Spanish-speaking people.
I would appreciate if you could help me in publicizing.


A big hug!
Edgar Luis Gomez.
G'Day Edgar

Hugs back!

Well, to start, here's your site hyperlinked.

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