It's only a couple more days until the comet that the Rosetta spacecraft is orbiting reaches its closest point to the Sun. As a preparatory celebration, the comet seems to be putting on a 'fireworks' display. (Nothing wrong with popping open the champagne a few days early...)
The mission to send a spacecraft to this comet was daring and bold. It launched into space over 10 years ago and since then it has performed some risky maneuvers, including being flung around Mars, settling into orbit around the comet and later deploying the Philae lander.
Now, the intrepid orbiter has taken this photograph of a burst of matter and dust from the interior of the comet. At first, this might seem alarming for an oddly shaped hunk of space rock. The Rosetta comet doesn't have a molten core like Earth, but there are other explanations for its active surface.
The regions that are emitting such high-energy jets are areas that were previously hidden from the Sun. Now that the comet is getting closer and closer to our Solar System's heat source, these parts of the comet are warming up, as is the ice that is now expanding into gas. The pressure from the expanded gas prompts an energetic blast out of the comet. These explosions drag dust with them into the atmosphere of the comet and then into space. And this blast looks mighty impressive, as you would hope with it being the "most dramatic outburst yet" observed by the Rosetta orbiter.
Three photos showing before, during and after the Philae outburst. ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.
The jet might seem localized in the photograph, but there were some far-reaching effects that Rosetta picked up on. The composition of the environment surrounding the comet was altered due to the influx of particles. More surprisingly, the outburst blew away the solar wind from around the comet's nucleus – its "heart" – for nearly 10 minutes. This was detected by a very sudden decrease in the strength of the solar wind's magnetic field.
“Usually, the jets are quite faint compared to the nucleus, and we need to stretch the contrast of the images to make them visible – but this one is brighter than the nucleus.”