Enigmatic Lights On The Moon

Enigmatic lights seen on the Moon are a classic example of a Fortean enigma. Called transient lunar phenomena (TLP), they have been a mystery and a source of wonder to skywatchers since the earliest times. And yet, as astronomer Peter Grego points out, despite a wealth of detailed observations we seem no closer to an understanding of what these anomalous flashes are.

Not long after the telescope was invented at the beginning of the 17th century, astronomers came to realise that the Moon, our only natural satellite, was not as dynamic a world as the Earth. The dark lunar tracts which early astronomers had somewhat optimistically called "maria" (seas) turned out to be nothing more than deceptively smooth plains of solidified lava. Much to astronomers' disappointment it became apparent that there were no appreciable expanses of water, though the new romantic marine nomenclature was retained, regardless - names like Mare Crisium (the Sea of Crises) and Oceanus Procellarum (the Ocean of Storms) were given in a vain attempt to grant the Moon an air of mystery and excitement.

In reality, the Moon's surface appeared solid and unchanging. The Moon possessed no appreciable atmosphere and there were no detectable signs of lunar life; the Church breathed a sigh of relief, having been spared the embarrassment of attempting to explain why the book of Genesis forgot to mention that our sister planet was teeming with the products of DNA.

This initial impression of the Moon as being a barren and entirely dead world has been propagated in the astronomical literature ever since Galileo first published his observations in 1610.2 It seems, however, that the Moon has been receiving unjustifiably bad astronomical press for nearly three centuries, for reports of its long-standing status rigor mortis have been greatly exaggerated. Lunar observers (mainly amateurs) have noticed that the Moon's surface is occasionally host to anomalous transient lunar phenomena (TLP) which have assumed a variety of forms, including isolated flashes or pulses of light, coloured glows and obscurations of portions of the lunar surface. Just why the science of astronomy has been unwilling to accept that our satellite occasionally displays obvious signs of activity is almost as big a mystery as TLP themselves.

There is no shortage of TLP having been observed by reputable astronomers. William Herschel, one of history's greatest astronomers - he discovered the planet Uranus in 1781 - observed a red glow in the vicinity of the crater Aristarchus on 4 May 1783, at a time when that feature was situated on the unilluminated lunar hemisphere.