|Discovered by||Arnold Schwassmann|
Arno Arthur Wachmann
|Discovery date||November 15, 1927|
|1908 IV; 1927 II; 1941 VI;|
1957 IV; 1974 II; 1989 XV;
|Orbital characteristics A|
|Epoch||March 6, 2006|
|Semi-major axis||5.986 AU|
|Orbital period||14.65 a|
|Dimensions||60.4 ± 7.4 km|
|Last perihelion||March 7, 2019|
|Next perihelion||October 31, 2033|
Comet 29P/Schwassmann–Wachmann, also known as Schwassmann–Wachmann 1, was discovered on November 15, 1927, by Arnold Schwassmann and Arno Arthur Wachmann at the Hamburg Observatory in Bergedorf, Germany. It was discovered photographically, when the comet was in outburst and the magnitude was about 13. Precovery images of the comet from March 4, 1902, were found in 1931 and showed the comet at 12th magnitude.
The comet is unusual in that while normally hovering at around 16th magnitude, it suddenly undergoes an outburst. This causes the comet to brighten by 1 to 5 magnitudes. This happens with a frequency of 7.3 outbursts per year, fading within a week or two. The magnitude of the comet has been known to vary from 18th magnitude to 10th magnitude, a more than thousand-fold increase in brightness, during its brightest outbursts. Outbursts are very sudden, rising to maximum in about 2 hours, which is indicative of their cryovolcanic origin; and with the times of outburst modulated by an underlying 57-day periodicity possibly suggesting that its large nucleus is an extremely slow rotator.
The comet is a member of a relatively new class of objects called "Centaurs", of which at least 400 are known. These are small icy bodies with orbits between those of Jupiter and Neptune. Astronomers believe that Centaurs have been recently perturbed inward from the Kuiper belt, a disk of Trans-Neptunian Objects occupying a region extending from the orbit of Neptune to approximately 50 AU from the Sun. Frequent perturbations by Jupiter will likely accumulate and cause the comet to migrate either inward or outward by the year 4000.
The dust and gas comprising the comet's nucleus is part of the same primordial materials from which the Sun and planets were formed billions of years ago. The complex carbon-rich molecules they contain may have provided some of the raw materials from which life originated on Earth.