Comet Biela
The comet that split in two and vanished, leaving only spectacular meteor storms to show where it had been.
Key facts
- Designation
- 3D/Biela
- Type
- Jupiter-family comet (destroyed)
- Orbital period
- about 6.6 years
- Closest to the Sun
- about 0.86 AU (about 129 million km)
- Farthest from the Sun
- about 6.2 AU
- Tilt of orbit
- about 12.5°
- Nucleus
- unknown; probably a few kilometres before it broke up
- Discovered
- first seen in 1772; recognised as periodic by Wilhelm von Biela on 27 February 1826
- Returns
- last seen in September 1852; the D in its name means it has disappeared
Orbit
Biela's Comet travelled round the Sun every six and a half years, close to the planets' plane, and its orbit crossed close to Earth's. That nearness made it the parent of a shower whose meteors come from the constellation Andromeda.
Size and nature
No one ever measured the nucleus, but the comet's fate shows how fragile these bodies are. When it returned in 1845, observers saw that it had become two comets side by side. In January 1846 the American naval officer Matthew Maury watched a companion beside it, and the two nuclei took turns to be brighter. At the return of 1852 both were found again, now about 2.5 million km apart. After that, neither was ever seen again.
History
Jacques Montaigne first saw the comet in 1772, and it was seen again in 1805. In 1826 Wilhelm von Biela, an Austrian army officer, observed it and showed it was periodic, the third comet known to return. Its disappearance set astronomers wondering where it had gone. The answer came in the sky.
Meteor showers
On 27 November 1872, when Earth crossed the comet's path, observers in Europe saw a storm of about 3,000 meteors an hour, now called the Andromedids. On 27 November 1885 an even stronger storm, perhaps 15,000 an hour, followed. These storms showed that a dead comet turns into a cloud of meteoroids, and they helped convince astronomers that meteor showers are the remains of comets. The shower has faded since, with small displays in some years such as 2011 and 2021.
Its meteor showers
- The Andromedids peak around 27 November historically; now weak, in late November to early December; about usually under 2; storms of thousands an hour in 1872 and 1885 an hour at best; about 19 km/s
Key dates
| Date | What happened |
|---|---|
| 27 February 1826 | Wilhelm von Biela observed the comet that bears his name and found it was periodic. |
| 27 November 1872 | An Andromedid meteor storm from the lost Comet Biela was seen over Europe. |
| 27 November 1885 | A second, stronger Andromedid storm fell from the remains of Comet Biela. |
Did you know?
An iron meteorite fell at Mazapil in Mexico on 27 November 1885, during the Andromedid storm. It is a coincidence: comets do not make iron meteorites.
The disappearance of Biela's Comet was one of the first clues that comets wear away.
The last sighting of either part was on 29 September 1852.