Edmond Halley Biography

Halley's Mercury transit observations strengthen interest in using accurately timed planetary transits to refine measurements of the Solar System.

Halley observes a transit of Mercury from Saint Helena and carefully records the event for later astronomical analysis.

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.

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Halley publishes his cometary calculations and predicts that the comet seen in 1682 will return in 1758.

Halley publishes a method for using future transits of Venus to calculate the Earth-Sun distance more accurately.

Succeeds Flamsteed as Astronomer Royal at Greenwich.

Halley's predicted comet is observed again, confirming his orbital calculation after his death and strengthening Newtonian celestial mechanics.

Halleys prediction of the comets return proved to be correct, although it was not seen until 25 December 1758, by Johann Georg Palitzsch, a German farmer and amateur astronome

The comet is first named in Halleys honour by French astronomer Nicolas Louis de Lacaille in 1759