# Talk:1 terametre

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## Untitled

a What is the actual diameter of Betelgeuse ? In the article 1e12 metres I see: 1200 million km; but the Betelgeuse article mentions this:

290 million km -- 1.9 AU -- Minimum diameter of Betelgeuse
480 million km -- 3.2 AU -- Maximum diameter of Betelgeuse

and these numbers are also copied in 1e11 metres. In [1] the NASA makes a claim that is compatible with the first measure, not the last ones: If placed at the center of our Solar System, it would extend past the orbit of Jupiter. I'm not an astronomer, so I can't tell which is true. -- FvdP 12:33 Sep 4, 2002 (PDT)

Encyclopedia Britannica claims

its diameter varies between 430 and 625 times the diameter of the Sun over a period of 5.8 years.

I don't have time to convert right now, but if this agrees with NASA, we should follow those numbers. AxelBoldt 12:37 Sep 4, 2002 (PDT)

If diameter(Sun) = 1 400 000 km then this 430..625 factor yields for the diameter of Betelgeuse: between 602 and 875 million km. The numbers in Betelgeuse might then be about the radius (but why ?). OTOH, the orbital radius of Jupiter is 780 million km according to Jupiter (planet) so the orbital diameter is 1500 million km. That does not fit NASA's claim. -- FvdP 13:03 Sep 4, 2002 (PDT)

In http://einstein.stcloudstate.edu/Dome/constellns/betelgeuse.html they say "The diameter of the star is about 650 times the diameter of the sun [...] the diameter of the star may vary as much as 60%.". This seems to be using 1978 data.

In http://www.gb.nrao.edu/~rmaddale/Education/OrionTourCenter/betelgeuse.html "Diameter 700 Million miles".

A trustworthy reference seems to be http://cfa-www.harvard.edu/cfa/ep/pressrel/betel97.htm with "Its diameter, based on the new distances recently reported by the European Space Agency satellite HIPPARCOS, is about 1500 times the diameter of our Sun." But that was 1997, maybe the estimates have changed since? AxelBoldt

The header of the article states that the page talks about magnitudes of 1,000 billions kms, when the list below start with approx. 1,000 millions kms. Not being an english native, I suspect this has to do with mixing american and english usages of the words "million" and "billion". I do not know the correct answer, could someone disambiguate ? Thanks in advance ! (WongoTheSane (talk) 14:15, 2 April 2008 (UTC)) Follow-up : I think it's just a typo and it should read "1,000 million kms", as the 1e+11m page correctly states 1e+11m being 100 million kms. I don't know how to edit this type of page, so I'll let someone more knowledgeable than I am do it. (WongoTheSane (talk) 14:22, 2 April 2008 (UTC))