Ask A Scientist© Astronomy Archive

Question:  What can you tell me about the supergiant Betelegeuse?
Rico.

Answer 1:  The red supergiant Betelgeuse is one of the largest (in physical
size, not mass) stars known. It is found in the constellation Orion; its
`official' designation is "alpha Orionis". Its mass is about 18 times that of
the Sun, and it is about 520 light years away. The name
"Betelgeuse" comes from the Arabic for "shoulder of the giant". It is a truly
enormous star, having a diameter 500 to perhaps 750 times that of the Sun. If
the Sun were replaced by Betelgeuse, it would extend past the asteroid belt!
Rcwinther

Answer 2:  Ahh, but how was the distance to Betelgeuse determined and who did
it?
Jlu

Answer 3:  The angular diameter of Betelgeuse was measured by Hanbury  Brown
using intensity interferometer. The other input is the true physical size of the 
star that can be computed from the spectral features.
Jasjeet.