The Summer
Triangle Part 1: Vega
If you look
directly overhead during summer evenings you will see a bright blue/white star.
This is Vega the brightest star in the constellation of Lyra the Lyre or Harp, which
according to Greek legend Apollo gave to the great musician Orpheus.
Vega is about
26 light years away, this means that the light entering our eyes this summer
left Vega in 1989. Anyone born in 1989 the light from Vega left the star the
year you were born!
It is
blue/white in colour, this means that Vega is hotter than our Sun. The colours
of stars tell astronomers which stars are hot and which are cool. Surprisingly
blue/white stars are much hotter than orange/red stars.
Although Lyra
is a small constellation there is a lot that can be seen without the help of a
telescope.
Just below Vega
you will see a small rectangle of stars the bottom right is beta Lyre or to
give its proper name Sheliak. This star varies in brightness and is referred to
as a variable star. It is quite easy to
watch it change in brightness every 13 days. There are many different kinds of
variable stars. Beta however was first identified as variable by the English
astronomer John Goodricke in 1784. Goodricke was deaf and unable to speak. He
is however one of the fathers of variable star astronomy.
To the left
and slightly above Vega is the star is epsilon, it is marked as e2, this star
is in fact double and if you look carefully you will see there are two stars rather than one.
Vega was
once our North Star but because the Earth wobbles very slowly the position of
the North Star changes. It takes the Earth 26,000 years to wobble once. Vega
will be the North Star again in about 12,000 years!
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