The Crab Nebula was reportedly observed by Chinese Astronomers in 1054 as a new star brighter than the rest. Scientists believe that the observation by the Chinese was the actual Super Nova that had created the crab nebula. Inside is a pulsar spinning at a rate of 30 times per second. This nuetron star (an extremely dense object), the remnants of the original star, is only a few kilometers across, but roughly contains the mass of our sun.
The nebula lies some 6,500 light-years away (failry close in comparison to other astrological bodies) and has a diameter of 11 light-years and expanding at a rate of roughly 930 miles / second. (0.5% the speed of light). If disipation did not occur, it would hit the earth in 1.3 million years...providing both our solar system and the origin of the nebula had a constant for cosmic drift. If our calculations of distance are correct, the actual super nova happened sometime around 7,500 BC, but we didn't witness the light from the detonation until 1054.
Our condolences to those who died in the Super Nova, assuming there was a habitable planet in its orbit. Since our technologies weren't developed enough in 1054 to determine if there was, we'll never know if there was a guy named Bob delivering a pizza when the planet was obliterated by the shockwave of a Super Nova.