Stars And Constellations; Star Names - Celestron NexStar 90 MAK Instruction Manual

Stars and Constellations

There are some 6,000 stars visible to the naked eye.
Most of these stars can only be seen from locations
far from the bright lights of a city or town. If you
really want to see the stars, you either have to go to
Hollywood or get out of Dodge.

Star Names

Some of the brighter stars have proper names, but
most don't – there are just too many to give each
one a name. Instead, astronomers have devised a
system that assigns names to stars based on their
brightness and the name of the constellation they
belong to. Following a centuries-long tradition, the
brightest star in a constellation is designated by the
first letter of the Greek alphabet, Alpha, followed
by the genitive form of the name of its constellation.
For example, the brightest star in the constellation
Orion is called Alpha Orionis. It also has a proper
name: Rigel. (We'll talk more about constellations
later. Right now we're going to focus on individual
stars.) When the letters run out, stars are identified
by various alphanumeric designations.
A funny thing about Rigel: even though it's the
brightest star in Orion, its designation is Beta
Orionis.
Betelgeuse, another star in Orion, was a little bit
brighter, but improvements in photometers in the
th
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brighter star (it's possible that Betelgeuse might
have been brighter in the past, when astronomers
first began to designate stars with Greek letters).
Astronomers originally thought that
century revealed that Rigel is actually the
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