[net.astro] StarDate: September 9 The Loneliest Star

dipper@utastro.UUCP (Debbie Byrd) (09/09/85)

The loneliest star is back in the evening sky.  We'll tell you why this
star is said to be lonely -- after this.

September 9  The Loneliest Star

In some places it still feels like summer -- down here in Texas, for
instance.  But the skies are beginning to look like autumn.  One
well-known autumn star is Fomalhaut, the loneliest star in the southern
sky.  Fomalhaut is called "the lonely one" or "the solitary one"
because -- it's the only even-fairly-bright star in its large dark
patch of sky.

Fomalhaut is located about 24 light-years from Earth.  Besides being
solitary, it's notable for having a large proper motion through our
sky.  In other words, the star moves sideways across our line of sight
at an unusually fast rate.  Most stars don't -- that's one reason we
sometimes refer to them as "the fixed stars." Even so, you'd waste your
time trying to see the sideways motion of Fomalhaut.  At its great
distance from us, its proper motion isn't evident to the naked eye.

Fomalhaut has three dim companions, and these four stars mark the
corners of a lopsided square.  The square is supposed to represent the
open mouth of a fish, and the constellation that contains Fomalhaut is
named Piscis Austrinis, or the Southern Fish.  As is often the case,
the rest of the constellation looks nothing like a fish!

If you look for Fomalhaut, you'll probably agree.  You'll find this
star easy to pick out because it's bright and solitary.  It's now
peeking up in the southeast in mid-evening, and it travels in an arc
across the southern sky throughout the night.  As autumn draws near,
Fomalhaut will be rising even earlier.


Script by Deborah Byrd.

(c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin