Sunday, Jul 27, 2025

Philolaus Philolaus is an interesting crater, partly because the bolide that created it struck directly over another, older crater, Philolaus C, and partly because lunar craters, like human craters, are very similar in general shape but have many details that differentiate them from one another. Philolaus Crater, 70 km in diameter, at first glance resembles Anaxagoras, Tycho, and many other large craters, but the crest of its rim has deviations from the perfect circumference that give it unique characteristics. Each of these step-like features marks a section of the rim wall that was fractured and then slid to the ground, creating a terrace or simply generating a mass of accumulated debris. Some chunks of rock—actually small mountains a few kilometers wide—rolled down the rim wall of the crater and settled inside; they can be clearly seen in the accompanying photo. The absence of an atmosphere meant that no sound was produced when these giant rockslides occurred, but many moonquakes were produced by these landslides, creating a temporary dust cloud above the crater. Photo and text: Avani Soares