Four years ago, comet-hunting spacecraft, Rosetta, took a final swan dive into the face of the comet 67P/Churyumov-Gerasimenko. It was the dramatic culmination of the European Space Agency’s twelve-year mission to study the icy object.
While Rosetta may be gone, its memory lives on in data. Scientists continue to analyze these data, collected from its time around and on the icy dirt ball, transforming scientists’ understanding of tiny interstellar objects like comet 67P — and confounding expectations
A new analysis of emissions from the comet’s gassy “coma” published Monday in Nature Astronomy marks yet another unexpected discovery: the first-ever observed aurora on a celestial object aside from moons and planets.
The discovery could enable scientists to better observe such objects in the future, and protect spacecraft and satellites against rogue solar radiation.
Auroras on Earth take place when charged particles from the Sun take a ride on our the planet’s magnetic field lines all the way up (or all the way down) to the north and south poles. As these solar particles bounce off molecules in the Earth’s atmosphere, they jump between different parts of the visible light spectrum.
This activity creates billowing and beautiful curtains of reds, greens, and blues in the upper atmosphere. Similar auroras have also been observed on Mars, and Jupiter’s moons Ganymede and Europa, but never before on a stellar object like a comet.