C/1874 H1 (Coggia)

Lore & Background

The comet was discovered by Jérôme Eugène Coggia on 17 April 1874 at the Marseille Observatory. Throughout late April and May, it was closely observed by many astronomers including Winnecke, Tempel, Rayet, Schulhof, Rümker, Schmidt, Bruhns, Christie, and Dreyer. In mid-May a faint tail developed, and by early June the comet became visible to the naked eye. Its brightness reached magnitude 4 by the end of June, and by early July the tail had grown to 6°, extending to 45° by July 16. The tail was straight and narrow, stretching 1° to 2° at its end.

On July 21, Trouvelot observed undulations in the tail, describing it as shortening and extending, with rapid vibrations and waves of light that lasted over an hour. The comet moved rapidly southward from July 16 to 23, becoming difficult to observe in the northern hemisphere; Schmidt made the last northern observation on July 23 in Athens. It became visible in the southern hemisphere on July 27, with observations in South Africa and by Robert L. J. Ellery in Australia. John Tebbutt observed it from August 1 to October 7, and John M. Thome made the final observation on October 19 at Córdoba, Argentina.

Reader's Guide

C/1874 H1 (Coggia) holds significance as the first bright comet studied with the spectroscope, a relatively new instrument at the time. Spectrographic observations from May to July 1874 by Huggins, Secchi, Lockyer, Rayet, and Wolf initially showed only a continuum, but by mid-June the three typical comet spectral bands were detected. The comet's orbit, calculated by Josef von Hepperger in 1882 using 638 observations over 185 days, is elliptical and inclined about 66° to the ecliptic. Its perihelion occurred on 9 July 1874 at 0.676 AU from the Sun, and its closest approach to Earth was on 23 July at 0.29 AU. The comet also appears in cultural records: Gerard Manley Hopkins wrote a journal entry about it on 13 July 1874, Mark Twain satirized public fear of the comet in his short story 'A Curious Pleasure Excursion,' and it was observed by members of the 1874 Black Hills Expedition led by Lt. Col. George Armstrong Custer, with accounts recorded in the diary of James Calhoun and a newspaper article in the New York World.

Did You Know?

• On July 21, Trouvelot observed undulations in the tail that lasted over an hour, with the tail appearing to shorten and extend repeatedly.
• The comet made its closest approach to Earth on 23 July 1874 at about 0.29 AU (43 million km).
• Gerard Manley Hopkins wrote a journal entry about Coggia's comet on 13 July 1874.