The European Space Agency's Rosetta has given us a more detailed understanding of comets and provided us with spectacular images of comet 67P/Churyumov–Gerasimenko during its two years of orbit around the object. The probe was crashed in September 2016, but it still provides some unexpected views.
The latest one is animated and was put together by Twitter user landru79. It shows what appears to be a “snowstorm” falling on comet 67P. What we are seeing is the dusty atmosphere of the comet illuminated by the light of the Sun. The probe is roughly 13 kilometers (8 miles) from the surface and the single images from the OSIRIS Cam that make up this GIF were taken over the space of about 25 minutes.
The GIF proved very popular online and started a lively discussion on the nature of the background objects seen disappearing behind the comet. Fortunately, astronomers from the European Space Agency (ESA) were at hand to explain what we see. Mark McCaughrean, a senior advisor for science and exploration at the ESA got involved. He confirmed that the objects are stars. OSIRIS Cam was pointed towards the Canis Major constellation and captured a few star clusters like NGC 2362 (at the top of the image) and NGC 2354 (near the middle).
The stellar field moving vertically as the comet rotates and the probe moves, combined with the swirling dust close to the camera, gives the impression that Rosetta is going through a flurry of flakes. The final footage looks like an old film, with snow silently falling on a cliff as the camera pans away.
Rosetta was the third cornerstone mission of ESA’s Horizon 2000 strategy and carried Philae, the first human probe that successfully landed on a comet. Rosetta’s observations were key to discovering that the water on Earth didn’t come from comets. The last image that Rosetta sent before its crash was taken when the probe was only 5 meters (16 feet) above the surface.
The author is now trying to create a color version of this little video but he’s unsure if it will work. Another Twitter user, lennutrajektoor, replied to this new undertaking with: “Jesus! Even this result is insane. I mean insane! Totally. I think I need a 10h version of it!” And we wholeheartedly agree.