The Moon is a beautiful example of a rocky planet - and it is one that practically is not being altered by geological forces. Most lunar landforms date back to the early days of our solar system: look at the moon's how you look too far back in time. Let's look at an old and huge training that would be famous, if you were located in a more easy to see location.

Humboldt (Imbriam period, 3.8 to 3.2 billion years ago) is one of the largest craters (207 km diameter) with a massive central system well defined and also exposed, other craters of this size, as Clavius, has its systems massif Central buried. The core is considered as representing a 10% increase in the diameter of the crater, so that the central peak may have been formed from material excavated over 20 km depth of the lunar crust!

Provocatively located on the eastern limb, Humboldt just the tips for terrestrial observers of the wonders it contains. With its 207 km in diameter, Humboldt approaches the transition size where large craters assume some of the morphological characteristics of the impact basins. Humboldt is also a major craters fractured ground (FFC), and modified by the intrusion of magma leak to the surface. The raised floor is presumably formed by rilles (see photo Apollo attached) and dikes that led the lava to the surface. In four places pyroclastic eruptions deposited dark gray material along the edge of the floor.

A concentric crater (see photo Apollo 15) absolutely perfect, 6.7 km wide, has two normal surrounding craters. All these three craters are slightly raised and its interior walls are very similar. Because one of the neighbors is slightly smaller and slightly larger than the other concentric crater seems reasonable to speculate that the concentric crater has exactly the right diameter and depth to interact with the floor and build layers of the inner ring somehow . But the inner ring seems rounded - like a donut, not like a normal kidney impact crater - so it might be some kind of volcanic deposit. In reality the formation mechanism of these concentric craters is not well explained and wait for a response.

This concentric crater is one of my next targets when hope in a libration and favorable illumination angle can shoot it.

Source: Whitepeak Observatory, Tacoma, WA

LPOD - Charles Wood

Wikipedia - Humboldt Crater

Sydney Observatory - Nick Lomb

Text and adaptation: Avani Soares