Transient Lunar Phenomena: Regularity and Reality

TL;DR

This paper reviews historical reports of transient lunar phenomena (TLPs), analyzing their distribution and potential causes, and finds strong evidence that many TLPs are real lunar surface events correlated with outgassing sites.

Contribution

It provides a comprehensive analysis of TLP reports, demonstrating that a significant portion are likely genuine lunar surface phenomena and correlates TLP locations with lunar outgassing evidence.

Findings

~50% of TLP reports involve crater Aristarchus.

>80% of reports are consistent with real lunar phenomena.

Robust TLP sites strongly correlate with lunar outgassing locations.

Abstract

Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled. A review of TLP reports shows regularities in the observations; a key question is whether this structure is imposed by human observer effects, terrestrial atmospheric effects or processes tied to the lunar surface. I interrogate an extensive TLP catalog to determine if human factors determine the distribution of TLP reports. I divide the sample according to variables which should produce varying results if determining factors involve humans e.g., historical epoch or geographical location of the observer, not reflecting phenomena tied to the lunar surface. Regardless of how we split the ample, the results are similar: ~50% of the reports involve crater Aristarchus nd vicinity, ~16% from Plato, ~6% from other recent, major impacts, plus a few at Grimaldi. Mare Crisium produces a robust signal for three of five averages of up to 7% of the reports (however, Crisium is an extended feature). The consistency in TLP report counts for specific features indicates that >~80% of reports are consistent with being real (perhaps excepting Crisium). Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D and Gassendi. TLP reports supporting these sites originate almost entirely after year 1955, when TLPs became more popular targets of observation and many more (and inexperienced) observers searched for TLPs. In a companion paper, we compare the spatial distribution of robust TLP sites of transient outgassing (seen on Apollo and Lunar Prospector). To a high confidence against the random hypothesis, robust TLP sites and those of lunar outgassing correlate strongly, further arguing for the reality of TLPs. [Abstract abridged.]