- Originally -- patterns of stars identified by ancient civilizations,
often to portray characters of legend.
- Today -- 88 regions which divide the sky in the same way the
states divide the United States.
- Note that the ``Big Dipper'' is not a constellation but is an
asterism. It is part of the constellation Ursa Major.
- The constellations visible on any given night depend on the time of
- Our perspective on the sky changes as the Earth orbits the Sun.
- It is impossible to see the constellations which lie
behind the Sun because daylight washes
out the stars.
- The Sun's apparent position in the sky shifts slightly
from day to day due to the motion of the Earth along
- A given star rises and sets four minutes earlier each day
- A star which is overhead tonight at Midnight will be overhead
at 10 p.m. one month from now.
- Note that today's constellations are temporary. Stars have random motions and over thousands of years will shift their relative positions.
Updated September 12, 2007