On July 29, the brightest jet jet ejected by a 2.5-mile (4-kilometer) comet 67P / Churyumov-Gerasimenko was recorded from Rosetta, an ESA spacecraft on an orbital tug. This is her brightest flash since the arrival of Rosetta on August 6, 2014.
Most 67P images with degassing and reactive emissions require graphic processing so that these processes become visible to the naked eye, but the latter does not require such processing. OSIRIS, a high-resolution camera on the Rosette, without any problems shot the entire show from a distance of 115 miles (186 kilometers).
Sudden emissions were recorded by Rosetta earlier, for example, on March 12, but today this is the most significant.
"This is the brightest jet we have seen," says Carsten Güttler, a member of the OSIRIS team at the Max Planck Institute for Solar Research, Göttingen, Germany. "Usually the jet streams are quite faded compared to the comet's core, and we have to enhance the image contrast to make them noticeable, but this one was brighter than the core itself." As comets approach the Sun, their surface is heated by the action of solar radiation. It melts the material of the comet under its shell, which sublimates (that is, turns from ice directly into gas) and shoots out with ice particles with high reflectivity.
Such emissions not only create bright streams, but also provoke activity in the dusty environment of the comet's nucleus, which, in turn, interacts with the solar wind.
On August 13, at 02:03 GMT (it is 22:03 on Wednesday, August 12, North American EST), comet 67P will be in perigee, that is, at the point closest to the Sun in its 6, 5-year orbit. It will be 115.5 million miles (186 million kilometers or 1.24 astronomical units) from the Sun before it starts its way back, bypassing the orbit of Jupiter. Fortunately for us, Rosette and Phil will accompany and closely observe its evolution in this dramatic “hot” part of her journey.