Quirks & Quarks

Comet outbursts likely due to avalanches, not geysers

Never before seen views of the comet 67P have given scientists information on what causes bright rays to shoot up from a comet's surface
This image of Comet 67P/Churyumov–Gerasimenko was captured by Rosetta’s OSIRIS narrow-angle camera on 12 August 2015 at 17:35 GMT, just a few hours before the comet reached the closest point to the Sun. The image was taken from a distance of about 330 km from the comet. The comet’s activity, at its peak intensity, which we now know is due to avalanches on the comet’s surface. (ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)
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If you've been keeping tabs on the results of the Rosetta mission that got unprecedented views of the comet 67P, you've probably seen images of outbursts from the comet. These outbursts look like bright rays shooting off the comet. Until now, it was thought these outbursts might be the result of geysers exploding through the comet's surface, releasing ice and gas. But this week, we learned that is likely not the case. It turns out those outbursts are the result of avalanches occurring on the comet's surface. Dr. Jordan Steckloff from the Planetary Science Institute presented his findings at the joint 48th annual meeting of the Division for Planetary Sciences of the American Astronomical Society and 11th annual European Planetary Science Congress held this week in Pasadena, California.

This is just the latest discovery demonstrating the role avalanches play on comets. The picture that's emerging could forever change how you think about these heavenly bodies.

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