|A composite image of the Crab Nebula showing the |
X-ray (blue), and optical (red) images superimposed.
A pulsar creates a magnetic field a million times more powerful than earth’s. It also creates powerful beams of electromagnetic radiation emanating from its two poles. The reason that pulsars pulse is because they are rotating. As they rotate, we detect these jet of radiation at regular intervals, much in the same way that a lighthouse works.
|Because a pulsar rotates about an axis that is not |
aligned with its magnetic poles, an observer will see
regular pulses of radiation as the magnetic poles
come in and out of sight.
The first pulsar was discovered in 1967 by Jocelyn Bell and Antony Hewish. At first they were perplexed by the regularity of the pulses, and named their find LGM-1 which stands for little green men. Some thought that pulsars might be radio beacons from alien civilizations and it wasn’t until about a year later that astrophysicists were able to determine what was really going on.