Why a Comet’s Head Is Green, but Its Tail Is Not
The New York Times
In a lab with lasers, scientists worked out a multi-chromatic mystery observed around the solar system.
The head of a comet often glows green; the tail mostly does not. That includes Comet Leonard, which made its closest pass to the sun on Monday and is heading away again.
A team of scientists have now come up with a detailed explanation for this multi-chromatic behavior. The molecule responsible for the emerald hue gets blown apart by sunlight within a couple of days of being created near the comet’s core, leaving almost nothing to glow green in the tail.
“We showed exactly how that happens in the lab by using UV lasers, measuring exactly how the molecule blows apart,” said Timothy W. Schmidt, a professor of chemistry at the University of New South Wales in Australia.
