Why comets glow green, but their tails don't

An international team of scientists led by the University of New South Wales in Sydney has addressed the question of why the bodies of comets have a greenish shimmer occurs, but does not continue in the tail of the heavenly bodies. They tested a guess , which the German-Canadian physicist Gerhard Herzberg in the 1930s. Herzberg suspected the dicarbon molecule as the cause – and he is right, as reported by Popular Science .

Dicarbon produced in the laboratory

Dicarbon are z white connected carbon atoms . On earth this connection is extremely fleeting. However, the team of researchers was able to generate it for experiments in the laboratory at short notice. That wasn’t possible in the 1930s. As it turns out, dicarbon creates a green sheen under sun-like light.

Ethyne splitting

On comets, the molecule is created by splitting of ethine . This gas, made up of two carbon and two hydrogen atoms, is stored in the ice of the comet. The hydrogen evaporates when exposed to sunlight, what remains is dicarbon. However, this substance also breaks down into individual carbon atoms when exposed to solar radiation. Because the dicarbon does not move far enough from the comet can, until that happens, the comet’s tail remains without a greenish sheen.

As predicted

The stronger the solar radiation, the smaller the greenish shimmer that surrounds comets. “I think it’s unbelievable that someone in the 1930s ponders has that that’s what probably happens and 90 years later we find out that it really is “, says study director Jasmin Borsovszky . The research report was published in the journal PNAS .