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MPC Theatre: Comet Chasers
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1995-05-25
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Halley's Comet is certainly the most famous of all comets. It has been observed at every
return by people all over the world since 164 B.C..
Halley's comet was first sighted by ancient
Chinese astronomers in 1059 B.C..
However, it was not until centuries later that astronomers
realized that comet Halley was in a circular orbit, and returned at regular intervals.
Edmond Halley, the English astronomer, observed the comet in 1682. He calculated the orbit,
and realized that it was very similar to the orbits of comets previously observed in 1607 and 1531.
Based on this information, Halley felt fairly secure in predicting that the comet would return once
again in 1758.
On Christmas eve of 1758 long after the death of Edmond Halley, a German amateur astronomer
spotted the comet. Halley's Comet, as it came to be known, reached its closest approach to the
Sun in March 1759, well within the limits of error given by Halley. This was the first time that the
return of a comet had been predicted. Before this, it was generally believed that comets traveled
in straight lines.
Halley's Comet was photographed for the first time in 1910, and was not observed again until
October, 1982. As Halley made its closest approach to the Sun in 1986, an armada of
international spacecraft intercepted the famous comet in space.
Two Russian spacecraft called VeGa 1 and VeGa 2, two Japanese spacecraft called Sagikake and
Suisei, and a European spacecraft called Giotto formed the fleet of space probes that investigated
Halley's Comet. The most daring of these probes was Giotto, which thrust straight through the
coma of the comet and survived with only a little damage to some instruments.
Unfortunately for viewers on Earth, Halley's visit in 1986 was not a spectacular sight, as the
comet approached the Sun opposite from the Earth's orbital position. Halley's Comet will return
again in the year 2062, and will no doubt be examined even more closely than before.
In the year 2138, Halley's Comet will pass close to the Earth, providing a dazzling show with a
bright tail millions of miles long. Particles from the comet's tail may even fall on the Earth,
creating luminous meteor showers in the night sky. However, as with all comets and asteroids
that cross the orbit of the Earth, it will also serve as a reminder of the dangers posed by these
wandering bodies.