Biela's Comet

Lore & Background

The comet was first recorded on 8 March 1772 by Jacques Leibax Montaigne and independently discovered during the same apparition by Charles Messier. It was also recorded in 1805 by Jean-Louis Pons but not recognized as the same object at the time. Around 9 December 1805, it passed about 0.0366 AU from Earth. After that apparition, Gauss and Bessel attempted to calculate a definitive orbit, and Gauss and Olbers noted a similarity between the 1805 and 1772 comets but could not prove a link.

Wilhelm von Biela, an army officer, 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. It was only the third comet known to be periodic, after comets 1P/Halley and 2P/Encke. The comet was named after Biela, though there was controversy due to independent discovery by Jean-Félix Adolphe Gambart, who provided the first mathematical proof linking the 1826 and 1805 comets, and a third claim by Thomas Clausen. Olbers in 1828 predicted a probable collision with Earth in 2500 years, which became the framing story of The Year 4338: Petersburg Letters.

The comet appeared as predicted in 1832, first recovered by John Herschel on 24 September. Orbital calculations by Olbers and Marie-Charles Damoiseau showed the coma would pass through Earth's orbit around October 29 but at a distance of about 0.55 AU, creating public alarm that François Arago allayed by noting Earth would not reach that point until November 30. In 1845, the comet was rediscovered by Francesco de Vico, and by January 1846 observers noted it had split into two components, which alternated in brightness and developed parallel tails. In 1852, both components were again observed, with 'Comet A' last detected on September 26 and 'Comet B' on September 29 by Otto Wilhelm Struve. Neither part was found at subsequent returns.

Reader's Guide

Biela's Comet holds a significant place in cometary history as one of the first three periodic comets identified, and as the first observed to split into two distinct nuclei. Its disintegration and disappearance after 1852 provided a dramatic demonstration of cometary evolution and destruction. The comet's intersection with Earth's orbit made it a focus of public and scientific attention in the 19th century, generating both fear and fascination, particularly during the 1832 apparition when calculations of a potential collision caused widespread alarm.

The comet's legacy endures through the Andromedid meteor shower, which was observed as a brilliant display of 3,000 meteors per hour on 27 November 1872, produced by the breakup of the comet. This event linked cometary disintegration directly to meteor showers, a key insight in understanding the relationship between comets and meteoroids. Although the Andromedids have since faded due to gravitational perturbations, the comet's remnants may still exist as dormant fragments. Searches in the later 20th century, including those using calculations by Brian G. Marsden and Zdeněk Sekanina, have not definitively recovered the comet, but the possibility that fragment A at least may survive as a dormant comet remains open. The comet also inspired literary works, including Edgar Allan Poe's The Conversation of Eiros and Charmion.

Did You Know?

• Biela's Comet was only the third comet known to be periodic, after Halley and Encke.
• The comet split into two nuclei observed in 1846 and 1852, and has not been seen since.
• Its remnants produce the Andromedid meteor shower, which peaked at 3,000 meteors per hour in 1872.
• In 1832, public fears of a collision were allayed by François Arago, who noted Earth would not reach the comet's orbit until a month later.