Comet Outbursts: Are They Caused By Avalanches?

Comet outbursts are the outcomes of avalanches, a new research claims. The prevalent belief held by the scientific community for the outburst of comets is that erupting geysers cause them. A comet's surface is dramatically shaped by sunlight, and it's ice melts on coming closer to the sun, leading to the emission of large outbursts by the comet that looks similar to plumes of material. Until now, these outbursts were interpreted as erupting geysers.

A recent study, conducted by Jordan Steckloff from Arizona's Planetary Science Institute, however has suggested that comets cannot produce the internal pressure which is necessary for geysers. The researcher has also put forward the argument that comets do not have enough heat, even when they are at their closest to the sun. On the basis of his observations, Steckloff modeled a different scenario where the outbursts are linked to surface changes.

"Rapid asymmetric brightening events of comets have been observed for decades and have long been believed to be the result of some sort of eruption of materials from deep within the interior of a comet," said Jordan Steckloff. "However, there is a major problem with this model. There is no internal heat source on comets to power geyser-like eruptions. Instead, these outburst plumes are the natural result of avalanches."

According to the scientist, when the light from the sun collides with a comet's irregular surface, the frozen material changes into gas that leaves its surface in a weak breeze. Furthermore, when such an occurrence takes place at the base of cliffs and slopes on a comet, the material slides down and subsequently the sublimation breeze propels it upwards, which causes plumes.

Steckloff's model has been found to be consistent with the data gathered by European Space Agency's (ESA) Rosetta mission that crash landed on comet 67P /Churyumov-Gerasimenko last month. The scientist's approach to comet outbursts also reportedly makes it possible to further study the plumes and even measure the amount of material moved, as well as the surface location from where the plume originated. Steckloff added that comprehending the outbursting mechanism, "may allow the surface processes of distant comets to be studied from Earth through ground-based observations of their outbursts."