A TLP (Transient Lunar Phenomenon) is an unpredictable, rare, mysterious glowing light on the Moon.  The ‘Transient’ part of their name means that they’re very rare, and only show up for a very short time.  They’ve been seen since astronomers first pointed their telescopes at the Moon, but are so elusive that in hundreds of years they’ve only been photographed a handful of times.  They are a bit of a mystery, but one leading theory suggests that they are the sites of meteor impacts – an object 10cm’s across would strike with enough force to temporarily melt the lunar surface, causing it to glow like lava.  Whatever the cause, though, they show that for all our efforts and despite all our best technology, the universe still has plenty mysteries waiting to be solved.