Armagh Observatory, 13 May 1999

The announcement on 8th May of the discovery of the trans-Neptunian object 1998 HQ151 by British astronomer David Jewitt and co-workers using the huge 3.6-metre diameter Canada-France-Hawaii Telescope on top of Mauna Kea in Hawaii, brings the total number of these planetary building blocks or giant comets to one gross, 144.

The objects mostly move, like Pluto, in orbits of low eccentricities and inclination beyond Neptune, forming a 'belt' or disc just beyond the main planetary system. Ignoring Pluto - which many astronomers assume to be simply the largest so-called Edgeworth-Kuiper belt object (EKO) - the largest EKO so far known (1996 TO66) is more than 800 kilometres in diameter.

The existence of the Edgeworth-Kuiper belt was first proposed by the Irish astronomer Kenneth Edgeworth in 1943. Edgeworth was a later generation cousin of Lucy Edgeworth who married Romney Robinson, Director of the Armagh Observatory from 1823 to 1882. The Dutch-American astronomer Gerard Kuiper independently proposed the existence of a trans-Neptunian belt of comets in 1951.

FOR FURTHER INFORMATION CONTACT: John McFarland at the Armagh Observatory. Tel.: 01861-522928 (work), 01762-879549 (home).

Last Revised: 15th June 1999 WWW contact: webmaster@star.arm.ac.uk

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