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Twice each year we see meteor showers as the Earth ploughs through the stream of dusty particles that escaped from Comet Halley's nucleus in the distant past
It is 25 years since Halley's Comet last visited the inner solar system, reaching its closest point to the Sun between the orbits of Mercury and Venus on 9 February, 1986. The comet, more properly called Comet Halley, was a disappointing sight in British skies, certainly if we compare it with the spectacle of Comet Hale-Bopp, the great comet of 1997.
Now receding towards the farthest point in its eccentric 75 year orbit, Halley was some 4,200 million km distant in 2003, when its frozen quiescent nucleus was last imaged as a faint smudge a billion times too dim to be seen with the naked eye.
Halley's legacy remains; twice each year we see meteor showers as the Earth ploughs through the stream of dusty particles that escaped from its nucleus in the distant past and is now distributed along Halley's orbital path. One such intersection gives rise to the Orionids shower around 21 October, the other is happening now, as very swift Eta Aquarids meteors diverge from low in the E after 03:00 BST. The shower began about 24 April, lasts until 20 May, and peaks this Friday morning as one of the best of the year for observers at equatorial and southern latitudes.
Comet Hale-Bopp was about 4,600 million km away, beyond the orbit of Neptune, when it was photographed in December, the most distant comet ever observed. It has another 50 billion km to reach its farthest point and more than 4,300 years before it returns to the Sun.
