Some people are going to experience some big Independence Day fireworks shows tonight. None of them will rival the one that the Chinese saw on July 4, 1054 A.D. They witnessed the explosive (supernova) death of a massive star. The "guest star" that they saw was so bright that it became visible in the daytime for 23 days and at night it cast shadows!
The remnant of this colossal event is now known as the Crab Nebula(also called as M1 and NGC 1952).
Hundreds of years after the event was seen observations by Mt. Wilson/Palomar astronomer Walter Baade helped to tie the nebula to the eyewitness reports from the Chinese astronomers.
In honor of the 955th anniversary of the supernova being seen on Earth I give you 2 photos of the Crab Nebula.
This first image is a vintage (possibly 1959) photo from the 200-inch Hale Telescope.
Contrasting the vintage shot is a modern image, again taken using the Hale Telescope.
The modern image looks pretty different, that mostly because it was taken in near infrared light. So the colors seen in the image are not at all what your eyes would see because your eyes can't see into the near infrared.
The Crab Nebula is located approximately 6,300 light years away. It is some 10 light years across and is expanding at about 1,800 km/sec.
At the heart of the nebula lies the Crab Nebula pulsar. The pulsar is neutron star that spins 30 times per second. It is heavier than our Sun but only about 20 kilometers (12.4 miles) across! That makes the diameter of the pulsar a little bigger than the length of Palomar Mountain, yet it weighs more than the Sun.
The pulsar is arrowed in the zoomed version below.