Math in the Physical Sciences

Astronomy and Math

What astronomical event with mathematical significance occurred on December 25, 1758?

On December 25, 1758, the appearance of a comet we now call “Halley’s Comet” (or Comet Halley) proved a famous astronomer’s predictions (unfortunately, it was sixteen years after his death). From around 1695, Edmond Halley (1656-1742; also seen as Edmund Halley) carefully studied comets, especially those with parabolic orbits. But he also believed that some comets had elliptical orbits, and he thus theorized that the comet of 1682 (now Comet Halley) was the same comet that appeared in 1305, 1380, 1456, 1531, and 1607. In 1705 he predicted that the comet would appear again 76 years later—in 1758—a prediction that came true.

Such a calculation was a great feat in those days, with Halley even taking into account the comet’s orbital perturbations produced by the planet Jupiter. Even today, the comet maintains its 76-year cycle. Its last appearance was in 1986; it will again appear in the year 2062.


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