Comet IRAS–Araki–Alcock

A false colour image of Comet IRAS–Araki–Alcock in 1983, viewed in infrared light by the Infrared Astronomical Satellite (IRAS).

Comet IRAS–Araki–Alcock (formal designation C/1983 H1, formerly 1983 VII) is a small comet that, in 1983, made the closest approach to the earth (about 5,000,000 km) of any comet in 200 years; only Lexell's Comet, in 1770, and 55P/Tempel-Tuttle, in 1366, are thought to have come closer.

The comet was named after its discoverers – the Infrared Astronomical Satellite and two amateur astronomers, the highly-respected George Alcock of the United Kingdom and Genichi Araki of Japan (both men were schoolteachers by profession, although Alcock was retired). Alcock had made his discovery simply by observing through the window of his home, using binoculars.^[1][2]

During the closest approach the comet appeared as a circular cloud about the size of the full moon, having no discernible tail, and shining at a naked eye magnitude of 3-4. It swept across the sky at an incredible speed of some 30 degrees per day.

It is a long-period comet, with an orbital period of around 964 years, and is the parent comet of the minor Eta Lyrid meteor shower.^[3] This shower's radiant lies between Vega and Cygnus and produces 1 or 2 meteors an hour in mid-May with a peak between May 9 and May 11.

References

1. ^ 'Obituary of George Alcock' BBC News, 21-12/2000
2. ^ 'Outbreak of Comet Fever', TIME Magazine, 23-05-83. "I've discovered a wonderful star," commented Araki, "Now I've got to discover a wonderful wife."
3. ^ 'Eta Lyrids', Meteor Showers Online, accessed 21-11-08