[sci.astro] StarDate: November 21 The South Pole of the Sky

dipper@utastro.UUCP (Debbie Byrd) (11/21/86)

The south pole of the sky -- when we come back.

November 21  The South Pole of the Sky

The Earth is a globe -- and people on the southern half of the globe
don't see all the same stars we do.  Southern hemisphere stargazers
never see Polaris, for example, the star that marks the north pole of
the sky.  If you're at the equator, then Polaris is right next to the
northern horizon.  Farther south, Polaris is below the horizon.

But the southern half of the globe of the sky also has a pole -- an
area directly above the south pole of the Earth.  Unfortunately,
there's no visible star near the south celestial pole -- no pole star
for observers in the southern hemisphere.  Instead of a southern pole
star, the south pole of the sky is marked by what appears to the eye as
only empty space.

To find the direction north in the northern hemisphere, you just have
to find the star Polaris.  Polaris marks the direction nearly due north
for people on our half of the globe.  But finding due south in the
southern hemisphere isn't all that easy.  To locate the south pole of
the sky, southern hemisphere observers take a round-about route via the
Southern Cross -- a famous star grouping visible from that hemisphere.
They take the long axis of the Cross, and extend it out by about four
and a half times its length.  This line points to the south celestial
pole -- which still isn't easy to see since no star lies there to guide
your eye.

Script by Deborah Byrd.
(c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin