Lunar Landscape Luminescence.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lunar Landscape Luminescence. Cohen, Alvin J. Abstract Let us consider the possibility that the moon has never been differenti~ted. With this premise, it is likely that the lunar surface was originally composed largely of magnesium silicates. Magnesium silicate meteorites namely, the enstatite achondrites may well approximate the lunar surface and, in fact, may be of lunar origin. Many of these achondrites have undergone shock-brecciation similar to rocks in such craters in Quebec as Lac Couture, Clearwater Lakes, Manicouagan and New Quebec, and could well have been thrown off the moon during production of similar craters. The enstatite achondrites exhibit both red and blue luminescence (Derham, Geake, and Walker, Nature 203, 134, 1964). The red luminescence is similar to that observed near Kepler after a solar flare (Kopal nud Rackham, Nature 201, 239, 1964) and could be due to excitation of either lunar matter or stony meteoritic debris from an asteroid or nucleus of a comet. The red luminescence is probably due to the substitution of Mn II for Mg II in the symmetrical Mg octahedral site in the orthoenstatite structure. It is not improbable that the blue luminescence is related to the substitution of Mn II for Mg II in the distorted Mg octahedral position in the orthoenstatite structure. It has recently been observed that the ratio of blue/red luminescence increases in disordered enstatite achondrites compared to enstatite achondrites that have not become disordered (Reid, Bunch, Cohen, and Pollack, Nature 204, 1292, 1964). Disorder is interpreted here as resulting from a hypervelocity shock wave produced by impact collision which distorts in some way the environment of the symmetrical Mn II 50 that the red luminescing environment is either destroyed or converted to a blue type. It is suggested that magnesium silicates on the moon may exhibit both red and blue luminescence as do enstatite achondrites and that the ratio of blue to red luminescence as detected from probes may possibly be used as a guide for mapping the amount of shocked matter around lunar impact craters. The amounts of Fe II probably present in darker lunar areas would prevent the luminescence in these regions. Detection of large areas of luminescence of the types described in the lighter regions would preclude a granite moon, but not lay to final rest the old hypothesis of the separation of the moon from the earth by tidal attraction. A nongranite moon would make the earth the only possible source of tektite parent material. Publication: The Astronomical Journal Pub Date: 1965 DOI: 10.1086/109577 Bibcode: 1965AJ.....70R.135C full text sources ADS |