No. 137: SEP-OCT 2001
But they were wrong, too. Close-up inspection by modern spacecraft has revealed no snowy peaks or large bodies of water on Mars that might mirror the sun. But another possibility has now come to the fore. The Martian flares could be reflections of sunlight from flat, hexagonal crystals of water ice in the thin Martian clouds; the same crystals that create some of the solar halos and sun dogs seen on earth.
That this sort of specular reflection does occur was demonstrated on June 7, 2001, when a flare was actually photographed in the area of Edom Promontorium. The photography was possible because scientists had been watching this spot intently -- with cameras at the ready -- because a well-observed flare had occurred at this location in 1954, and calculations showed that conditions would be just right for the sun to be again reflected by clouds at this spot on June 7, 2001. It was a prediction that came true.
Sunlight reflected from Martian clouds cannot be the total answer, though. An area called Tithonius Lacus, for example, is the source of many flares, but it is too cold in this part of Mars for clouds of water-ice crystals to exist. No closed book here!
(Dobbins, Thomas, and Sheehan, William; "The Martian-Flares Mystery," Sky & Telescope, 101:115, May 2001. Anonymous; "Source of Flashes of Light Found," Fort Worth Star-Telegram, June 24, 2001. Cr. D. Phelps.)
Comment. The Martian-flare phenomenon is reminiscent of the "Perseus-flasher" discussions in 1987. (SF#53) The frequently observed flashes of light seen in the constellation Perseus turned out to be sun glinting off an artificial satellite.
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