Mysterious comet has been having multiple large outbursts

Amateur and professional astronomers have found that the comet 29P/Schwassmann-Wachmann has been experiencing an unusually large outburst recently. Normally, it has little outbursts spread throughout the year.

Comet 29P was discovered in 1927 and shortly thereafter was found to be orbiting the sun on a planet-like path in the space between Jupiter and Saturn. It was also found to be very large—approximately 60 kilometers across. Later, astronomers found that it behaved differently than other comets. Instead of shedding material as its outer layers melted during close fly-bys to the sun, it exhibited a kind of explosive behavior on occasion. Something was being ejected from the comet's interior, making the comet shine extremely brightly. The ejecta then fell back to the comet, adding a coating. Further study showed that periodically, a much larger outburst would occur and the comet would shine even more brightly. Such a huge outburst has been happening again, this time it started at the end of September.

Their research has shown that both the small outbursts and the large outbursts are unpredictable. In this latest outburst, there have been multiple eruptions and the comet grew in brightness to approximately 250 times that of its normal luminosity.

Notably, nobody knows why the comet erupts, though it does appear that the large outbursts work in ways similar to some volcanos. The ejecta from the small eruptions cover the exterior of the comet, creating a sort of shell. This, researchers suggest, leads to a build-up of pressure. Eventually, the pressure is strong enough to break through the icy crust, leading to a very large eruption.

In a novel twist, most of the research conducted regarding comet 29P has been done by amateurs with backyard telescopes. Time on the big telescopes has grown so competitive that most of the pros tend to focus on larger more important projects. The amateur astronomy community was hoping to learn more about the comet during this large outburst, however, as several professional teams requested and were granted time on the Hubble Space Telescope to peer at the comet. Sadly, these hopes were dashed as Hubble experienced technical problems that prevented it from pointing at the comet in time to catch its massive outburst in action.

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