Biela's Comet - Confirmation As Periodic

Confirmation As Periodic

It was Wilhelm von Biela, an army officer serving at the fortress town of Josefstadt, who observed the comet during its 1826 perihelion approach (on February 27) and calculated its orbit, discovering it to be periodic with a period of 6.6 years. At the time it was only the third comet known to be periodic, after the famous comets Halley and Encke. The comet was named after Biela, although there was initially some controversy due to a later but independent discovery by Jean-Félix Adolphe Gambart, who also provided the first mathematical proof linking the 1826 and 1805 comets (letters from Biela and Gambart were published in the same issue of the Astronomische Nachrichten). A third claim was made by Thomas Clausen, who had independently linked the comets.

The comet appeared as predicted during its 1832 apparition, when it was first recovered by John Herschel on 24 September. The orbital elements and ephemeris calculated by Olbers for this return created something of a popular sensation, as they showed that the comet's coma would likely pass through the Earth's orbit during a close approach on October 29. Subsequent predictions, in the media of the time, of the Earth's likely destruction overlooked the fact that the Earth itself would not reach this point until November 30, a month later, as pointed out by François Arago in an article designed to allay public fears. Despite this, the fact that Biela's Comet was the only comet known to intersect the Earth's orbit was to make it of particular interest, both to astronomers and the public, during the 19th century.

The 1839 apparition was extremely unfavourable and no observations were made.