Image of Comet Halley

In 1986, the European spacecraft Giotto became one of the first spacecraft ever to encounter and photograph the nucleus of a comet, passing and imaging Halley's nucleus as it receded from the sun. Image Credit: Halley Multicolor Camera Team, Giotto Project, ESA

Discovery

The first observations of comet Halley are lost in time, more than 2,200 years ago. However, in 1705, Edmond Halley was studying the orbits of previously observed comets and noted some that seemed to re-appear every 75-76 years. Based on the similarity of the orbits, he suggested these were in fact the same comet and correctly predicted its next return in 1758.

Overview

Comet 1P/Halley is perhaps the most famous comet—it has been sighted for millennia. Halley is even featured in the Bayeux tapestry, which chronicles the Battle of Hastings in 1066.

This comet takes about 76 years to orbit the sun once. The last time Halley was seen from the Earth was in 1986. That year, an international armada of spacecraft converged on the comet to take images and data.

Halley will not enter the inner solar system again until 2061. Each time that Halley returns to the inner solar system its nucleus sprays ice and rock into space. This debris stream results in two weak meteor showers each year: the Eta Aquarids in May and the Orionids in October.

Comet Halley's dimensions are 10 x 5 x 5 miles (16 x 8 x 8 kilometers). It is one of the darkest, or least reflective, objects in the solar system. It has an albedo of 0.03, which means that it reflects only three percent of the light that falls on it.

How Comet 1P/Halley Got Its Name

Comets are usually named for their discoverer(s) or for the name of the observatory/telescope used in the discovery. Since Edmond Halley correctly predicted the return of this comet -- the first such prediction -- it is named for him to honor him. The letter "P" indicates that Halley is a "periodic" comet. Periodic comets have an orbital period of less than 200 years.

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