Comet Aurora

24 Sep 2020

At [23rd September 2020] .. in a paper published in Nature Astronomy researchers describe how Comet Churyumov-Gerasimenko was seen to turn vaporous jets of water into aurorae. The Rosetta spacecraft, launched by ESA, observed the aurora whilst orbiting the comet. As the comet does not have a magnetic field, or any other comet yet known, they were loathe to identify the lights as true aurorae. Yet, the glow was certainly there - but not necessarily visible to the human eye. They shine at ultra violet wavelengths. It took years to figure out what was going on, we are told. They discovered that electric fields in the comet's atmosphere, or coma, can grab electrons from the solar wind and hurl them inwards. The electrons, on meeting water vapour molecules emitted by the comet, excite atoms of hydrogen and oxygen to produce the glow. They think other comets have similar aurorae.

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