Aristarchus is a prominent Lunar Impact Crater that lies in the North/Western portion of the Moon's Near Side. It is considered the brightest of the large formations on the Lunar Surface, with an Albedo that is nearly two times brighter that the one of most of all the other Lunar Features. In fact, Aristarchus is bright enough to be visible even to the naked eye, and it becomes dazzling in a medium/large telescope. It is also relatively easy to identify when most of the Lunar Surface is illuminated by the Earthshine only.
Aristarchus Crater lies at the South/Eastern Edge of the Aristarchus Plateau: an elevated Rocky Rise located within the Oceanus Procellarum which contains a number of Volcanic Features and that is also well known for the occurrence of a large number of (reported) Transient Lunar Phenomena (or TLPs), as well as for very recent emissions of Radon-222 Gas (emission which were duly registered and measured by the Lunar Prospector Spacecraft).
As additional reference points, we remind you that Aristarchus Crater is located just to the East of the Crater Herodotus and the Vallis Schröteri, and South of a system of narrow Sinuous Rilles named Rimae Aristarchus. Probably, the main reason for Aristarchus' brightness is that it is a (relatively, of course) young formation (such as approximately 450 Million Years old) and so the Solar Wind has not yet had enough time to darken the excavated material via the process known as "Space Weathering". The impact which created Aristarchus Crater likely occurred after the creation of the Rayed Crater Copernicus, but some time before the appearance of the beautiful Crater Tycho.
Aristarchus was originally named after the Greek Astronomer Aristarchus of Samos, by the Italian map maker Giovanni Riccioli. His work "Almagestum Novum", published in the AD 1651, gave to the, in that time known as "spot-shaped telescopic features" (such as the Impact Craters) the eponyms of famous Astronomers and Philosophers. Although the name of Aristarchus Crater has always been widely accepted and adopted, it actually did not become "official" (from an International point of view), until the International Astronomical Union (IAU) so decided to name it, during a General Assembly that was taken in the AD 1935.
As we already wrote hereabove, the Region of the Aristarchus Plateau (and the Crater Aristarchus in particular) has been (and still is) the site of many reported Transient Lunar Phenomena, with a total of 122 reports by the AD 2007: the highest number ever recorded for any Lunar Feature. Such a TLPs include, among others, Temporary Obscurations and/or bright Colorations of the Surface; the appearence of Star-like Shinings (either fixed or in slight motion) as well as isolated Flashes of Red, Blue and/or even Green Light. Official Catalogues (for instance the very famous NASA Technical Report R-277) mentioning these TLPs show that more than one-third of the most reliable observations came from Aristarchus Crater and its immediate surroundings.
In the AD 1971, when the NASA - Apollo 15 Spacecraft passed at a distance of about 110 Km above the Aristarchus Plateau, a significant rise in the amount of Alpha Particles was immediately detected, and these particles were and still are thought to be caused by the presence of huge amounts, in the whole area, of Radon-222: a radioactive and colorless Noble Gas that forms naturally during and as part of the normal Decay Chain of Uranium and/or Thorium; just out of curiosity, we know that the Radon-222 possesses a so-called "half-life" of only 3,8 days.
The Lunar Prospector Mission, afterwards, confirmed Radon-222 emissions from Aristarchus. However, still making reference to the occurrence of TLPs in the Aristarchus Region, we can say that some of these fascinating (and still not totally understood) observations, could also be explained by the occurrence of discrete Explosions (probably powerful Outgassings), or even to events (of course rare, nowadays) related to some Residual Lunar Volcanic Activity.
This frame has been colorized in Absolute Natural Colors (such as the colors that a human eye would actually perceive if someone were onboard the NASA - Lunar Reconnaissance Orbiter and then looked down, towards the Surface of the Moon), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.
