New data about Comet 67P/Churyumov-Gerasimenko from the European Space Agency's Rosetta spacecraft finally confirms what's been a long-held theory about where shooting stars come from: comets.
Although scientists have long believed that the dust and particles from comets creates the meteoroids that we see as streaking "stars" across the sky, this new data proves that theory.
Shooting stars are objects made up of interplanetary dust (IPD). They're classified as meteoroids when they measure smaller than asteroids. When these meteoroids enter Earth's atmosphere, they develop a tail behind them, which causes us to see a shooting star as a streak in the sky.
Rosetta's COSIMA instrument recently collected dust and particles from Comet 67P. An analysis of that dust showed the very same particles we find in the interplanetary dust that makes up shooting stars, including the annual Perseids from Comet 109P/Swift-Tuttle and the Leonids from 55P/Tempel-Tuttle.
These "fluffy and porous" particles are about .002 inches wide and rich in sodium.
"There has been a long-standing dispute of whether the source of IPDs are solely comets or also asteroids," says the European Space Agency's Rita Schultz. "Our results imply that they have cometary origin. Another source would not be required."
So how do comets build up all this dust? Comets are mostly dust and ice, with an outer dust mantel. As comets orbit the sun, temperature changes affect activity on the comet's surface. When the comet is farthest away, there is less activity, meaning that gases and vapors trapped within the comet are too weak to shake dust off. But as the comet gets closer to the sun, those gases and vapors heat up and reactivate, sending the dust flying into space.
Eventually, the comet completely sheds its dust mantle, which could be now happening to Comet 67P. This means that future dust collections made by Rosetta's COSIMA instrument could show a very different composition.
"This layer is being removed as the activity of the comet is increasing again," says Martin Hilchenbach, COSIMA principal investigator. "We see this layer being removed, and we expect it to evolve into a more ice-rich phase in the coming months."
Rosetta made history last year by becoming the first spacecraft to orbit a comet. It made history again when its Philae Lander touched down on the surface of a comet for the first time. Unfortunately, that mission didn't go according to plan and after bouncing on Comet 67P's surface several times, Philae ended up landing somewhere in shadow. This meant that Philae's solar panels didn't receive enough power to continue the lander's mission, so Philae powered down.
There is, however, a chance that Philae wakes up this spring and finishes the science missions it started in its first 48 hours on the comet's surface.
