January 4

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  1131: Polymath, scholar, mathematician, astronomer, philosopher, and poet Omar Khayyám dies.

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  1798: Physician and physicist Luigi Galvani dies. In 1780, he discovered that the muscles of dead frogs' legs twitch when struck by an electrical spark.

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  1820: Physicist John Tyndall dies of accidental chloral hydrate overdose. He studied diamagnetism, and made discoveries in the realms of infrared radiation and the physical properties of air.

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  1969: Black Panther Party members Fred Hampton and Mark Clark are shot and killed during a raid by 14 Chicago police officers. In January 1970, a coroner's jury will hold an inquest and rule the deaths to be justifiable homicide. Critics will contend that Hampton was assassinated.

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  1973: The Pioneer 10 space probe makes its closest approach to the planet Jupiter, at a range of about 132,252 kilometers (82,178 mi).