The Crab Nebula is the remnant from a supernova which exploded in 1054 A.D.
This event was recorded by Chinese and Arab astronomers, and perhaps by the
Anasazi natives in North America. The Chinese records indicate that this
exploding star was visible during the daylight for 23 days, and at night for
about 2 years. The red filaments faintly visible in this image are compressed
remains of the outer layers of the exploded star (the name "Crab Nebual" comes from
astronomical drawings in the mid-1800's, in which these filaments look like
legs on a crab), while the blue-white glow of the nebula is from high energy
electrons speeding along magnetic fields created by the "neutron star" left
behind by the explosion. This neutron star is the collapsed core of the original
star, now squeezed into a diameter of only about 30 kilometers.
It is so dense that a teaspoon of its material would weigh a billion tons on earth!
The rotational energy of the star being compressing into such a small body also
makes the neutron star rotate at an amazing 30 times each second. This neutron star
is visible in the image. Near the center of the nebula are two stars that appear very
close together; the one on the left is the neutron star whose explosion produced this
nebula. The Crab Nebula is 6300 light years away. It is 11 light years in diameter,
and expanding.



Image data:
Camera: SBIG STXL-11002
Exposure: 13 hours 20 minutes total
red, green, blue = 90 minutes each
Luminance = 255 minutes
Hydrogen alpha = 160 minutes
O-III = 120 minutes
Telescope: Hyperion 12.5"