ORGANIC molecules are not created in comets, say astrochemists. Instead, the
organics come from pristine molecular clouds that form stars.
When astronomers detected complex organic molecules around Comet Hale-Bopp in
1997, they wondered if they might have formed in the comet鈥檚 energetic
atmosphere. Now Steven Rodgers and Steven Charnley at NASA鈥檚 Ames Research
Center in California have shown that the chemical reactions needed are too slow
to compete with the destructive effect of ultraviolet light (Monthly Notices
of the Royal Astronomical Society, vol 320, p 61).
Rodgers says they must have formed over millions of years in the original
molecular cloud that gave birth to the Sun. 鈥淐omets are some of the most
pristine objects in the Solar System,鈥� he says.
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