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Crab Nebula
Pulsar Radiation
Blinking Pulsar
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Although the Crab Nebula has been studied with telescopes for hundreds of years,
it wasn't until 1967 that we began to understand the nature of the central engine
that powers the Crab Nebula and enables it to glow. In that year, Jocelyn Bell, a
student at Cambridge University in England, found a curious object in the
constellation of Vulpecula. It seemed to be a "star" whose light blinked on and
off, apparently much like a lighthouse beacon, with an amazingly precise
frequency of once every 1.33728 seconds.
What could possibly DO that, in the sky, with such accuracy? Soon others were
found, and astronomers jokingly called them LGMs for "Little Green Men." (What
else could possibly be responsible for such bizarre behavior?)
Shortly thereafter, one such beacon was discovered at the center of the Crab
Nebula, beating 30 times per second! Not only that, it could be seen throughout
the electromagnetic spectrum, from radio waves
through X-rays. Although later called "pulsars," it turned out that rotation is
responsible for the clock-like regularity of the pulses. And the star? Well, it
turned out to be something so strange and exciting that it almost defies
description....
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