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A '''Pulsar''' is a [[neutron star]] whose magnetic axis is not aligned with the rotational axis.  As a result, charged particles which accrete in a disk orbiting around the star's equator are ejected along the magnetic poles, sweep across the sky, and in a very few cases can be detected from Earth as regular pulses in the radio frequency spectrum.  Very often these pulses are spaced only a few [[millisecond]]s apart, indicating the incredible rotational speed of the pulsar.   

A '''pulsar''' is a [[neutron star]] whose magnetic axis is not aligned with the rotational axis.  As a result, charged particles which accrete in a disk orbiting around the star's equator are ejected along the magnetic poles, sweep across the sky, and in a very few cases can be detected from Earth as regular pulses in the radio frequency spectrum.  Very often these pulses are spaced only a few [[millisecond]]s apart, indicating the incredible rotational speed of the pulsar.   

In 1974 University of Massechusetts astronomer Joseph Taylor and his graduate student Russell Hulse discovered two pulsars in a very eccentric orbit around each other with a period of 7.75 hours.  Over the course of twenty years, their observations of the star's periastron advance (analogous to the perihelion advance of [[Mercury]] but a much larger effect as well as the increase in the orbital period helped confirm general [[relativity]], and the two researchers were  awarded the 1993 Nobel Prize in physics. <ref>David Darling.  ''Gravity's Arc'', 2006, John Wiley & Sons</ref>

In 1974 University of Massechusetts astronomer Joseph Taylor and his graduate student Russell Hulse discovered two pulsars in a very eccentric orbit around each other with a period of 7.75 hours.  Over the course of twenty years, their observations of the star's periastron advance (analogous to the perihelion advance of [[Mercury]] but a much larger effect as well as the increase in the orbital period helped confirm general [[relativity]], and the two researchers were  awarded the 1993 Nobel Prize in physics. <ref>David Darling.  ''Gravity's Arc'', 2006, John Wiley & Sons</ref>