Comet Halley
Comet Halley, officially designated 1P/Halley, is one of the most famous periodic comets and can be seen from Earth approximately every 76 years. Here are some detailed aspects of this comet:
Historical Observations
- First Recorded Sighting: The earliest known sighting of Comet Halley is from records in China in 240 BC.
- Edmond Halley: The comet was named after the English astronomer Edmond Halley, who, in 1705, correctly predicted its return after studying historical records and calculating its orbit.
- Notable Appearances:
- 1066: Mentioned in the Bayeux Tapestry, which depicts the events leading up to the Norman conquest of England, including its appearance in the sky.
- 1910: It was particularly bright and widely observed, leading to public fear due to the Earth passing through the comet's tail.
- 1986: This was the last time Comet Halley passed close to Earth. It was less visible from the northern hemisphere due to its position in the sky.
Physical Characteristics
- Nucleus: The nucleus of Comet Halley is estimated to be about 15 km long, 8 km wide, and 8 km thick.
- Composition: It contains volatile ices (water, carbon dioxide, carbon monoxide, etc.), dust, and rocky materials.
- Orbit: It has an elliptical orbit with a period of about 76 years, varying slightly due to gravitational perturbations by planets, especially Jupiter.
Scientific Interest and Missions
- Spacecraft Encounters:
- Giotto Mission: Launched by the European Space Agency in 1985, it flew by Comet Halley in 1986, providing the first close-up images of a comet nucleus.
- Vega Missions: Two Soviet spacecraft, Vega 1 and Vega 2, also rendezvoused with the comet in 1986, releasing landers that parachuted into the comet's atmosphere to study it.
Cultural Impact
- Comet Halley has appeared in various forms of art, literature, and even influenced naming conventions (e.g., the Halley Research Station in Antarctica).
- It has been an omen in historical contexts, often associated with significant events or changes.
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