Great Britain · Science / Astronomy. Chronological records rendered directly from the World History Database.
Halley is classified as a periodic or short-period comet; one with an orbit lasting 200 years or less. After a rough estimate of the perturbations the comet would sustain from the gravitational attraction of the planets, he predicted its return for 1758
This calculation enabled him to determine that the orbital elements of a second comet that had appeared in 1682 were nearly the same as those of two comets that had appeared in 1531 (observed by Petrus Apianus) and 1607 (observed by Johannes Kepler). Halley concluded that all three comets were
same object returning every 76 years, a period that has since been amended to every 75-76 years.
the
Halley's predicted comet is observed again, confirming his orbital calculation after his death and strengthening Newtonian celestial mechanics.
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