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Going Green

30 September 2013

Comet ISON has gone green – see http://phys.org/print299762513.html

A circular green coma has developed as the comet gets closer to Mars and and a dust trail is visible too (in telescopes). Green is apparently a sign of stirring activity on the comet as it approaches closer to the Sun. The Great Comet of 1811 had a coma 864,000 miles across – indicating ISON has some way to go. Cyanogen and diatomic carbon are colourless gases that flouresce into green when excited by energetic ultra violet light in sunlight (it is thought). Cynagen is a poison and diatomic carbon is not much better – a corrosive acide found in comets and also in vapour from high energy electric ars.

At first I thought I hadn't read that right and re-read the offending sentence. Comets emit a gaseous vapour that is the same as one emitted by electric arcing.

Very bright comets visible to the naked eye often display multiple colours that change chameleon fashion over time. Dust trails can glow pale yellow – like the yellow cloaks of Celtic gods described in Patrick McCafferty and Michael Baillie, The Celtic Gods : comets in Irish mythology. In addition, the solar wind sweeps back molecules from the coma into a second 'ion' tail that glows pale blue – no wonder comets were described in terms of the colourful quetzl bird of Mexico (Quetclcoatl).

From Universe Today

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