Date: Prior to 1993
What is the closest star to the sun. Some sources say Alpha
Centauri and others say Proxima Centauri is the closest. Both are reliable,
but I am confused about which is the closest star?
The name "Alpha Centauri" actually denotes a triple star system
in the constellation Centaurus (it appears as a single star to the naked eye).
Two of these stars, denoted Alpha Centauri A and B, are very similar to the
sun and are approximately 4.336 light-years away. They orbit each other
(better said, they orbit their common center of mass) with a period of about
80 years. Then, orbiting this pair is a small, faint star only a tenth the
size of the sun. This star takes one-and-a-half million years to orbit the
larger pair; at the moment it is closer to us than the other two, a mere 4.205
light-years away. Because it is the nearest star to the sun, it is named
Proxima (from the Latin word for "nearest") Centauri. This information came
from "Astronomy: The Cosmic Journey", an astronomy text by William Hartmann.
I did not know this stuff myself until now!
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Update: June 2012