Astronomy: Glazing the Moon

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While photographing the moon's surface with a special stereo camera, Astronaut Neil Armstrong was fascinated by several glassy patches that glittered like tiny bright mirrors. "I noticed them in six or eight places," Armstrong explained, "always in the same kind of place—at the bottom of a crater." Last week Cornell Astronomer Thomas Gold offered a dramatic explanation. The moon, he says, may have been scorched by a huge flare-up of heat and light within the solar system.

Since the patches have survived on the lunar surface despite the moon's constant bombardment by micrometeorites and solar particles, Gold calculates that the event was relatively recent—perhaps less than 30,000 years ago. It probably lasted only ten to 100 seconds. The small craters show the effect of the blast because they are natural heat traps. What was the origin of this fiery outburst, which Gold figures was 100 times more powerful than ordinary sunlight? Writing in the current issue of Science, Gold speculates that it came from the sun itself, possibly as the result of a collision with a large comet.

Puzzling Conditions. That kind of cataclysm would not have left any obvious scars on the face of the earth, Gold explains, since much of the ultraviolet radiation would have been blocked off by the earth's atmosphere. But, he adds, the atmosphere itself might have been disturbed or even partially swept away. The explosion, for example, might have blown off some atmospheric helium. It could also account for puzzling conditions on other planets, such as the lack of measurable nitrogen on Mars. Perhaps the most spectacular possibility raised by Gold is that one whole side of Mercury, the closest planet to the sun, might have been seared by the blast.

Since a trip to Mercury is still far off, Gold hopes for more immediate confirmation of his theory. An opportunity may come during the Apollo 12 mission in November. If the astronauts discover glazing of the same age in a different area of the moon far from Tranquillity Base, Gold says, he will be satisfied that such a solar catastrophe actually occurred.