Does the moon spark like a Life Saver?

Does the moon spark like a Life Saver?

For centuries, amateur and professional astronomers alike have reported observing sudden brightenings or flashes on the surface of the Earth's moon. These events are sometimes described merely as "lunar transient phenomena," for lack of a universally accepted way to explain them. Scientists seeking an energy source for the strange flashes -- which observers have seldom if ever found while deliberately looking for them -- have speculated on causes, including light emissions stimulated by solar ultraviolet photons, accelerated particles from the tail of Earth's magnetic field, and processes somehow associated with solar flares.

Now, Richard R. Zito of Lockheed Missiles and Space Co. in Sunnyvale, Calif., proposes yet another possible origin -- the rocks of the moon itself. Inert gases such as helium would be the likeliest to produce such glows, he writes in the December ICARUS, adding that "surface rocks returned from the moon by Apollo 11 show inert gas concentrations 20 to 10,000 times larger than those of the terrestrial values."

The gases can be released through cracks created by heat stresses, such as those that occur when parts of the lunar surface pass from darkness into sunlight, Zito points out. Many of these surface flashes, he says, have appeared in or near craters associated with fault systems. As for the energy to light up the little puffs of gas, he says, "it has recently been observed that flashes of light are emitted during the laboratory fracturing of rocks."

According to Zito, the flashes appear to take place when energetic electrons are emitted from freshly fractured surfaces. He also notes that "a similar effect is known to occur when Wint-O-Green Life Savers are cracked" (SN: 7/30/88, p.78).

Furthermore, the fracturing of a rock sometimes produces not only the optical pulse but also "a curious radio emission" with frequencies ranging from about 900 to 5,000 hertz, Zito says. This is "believed to be due to the rotational, vibrational and linear motions of charged fresh surfaces created during cracking" -- in other words, a rearranging of the rock's crystal structure. The wavelengths of emissions at these frequencies ought to be detectable by an antenna aboard a moon-orbiting satellite, he says. If Zito's hunch is correct, the radiation pattern should resemble that observed in the laboratory studies.