Giovanni Baptista Riccioli was a Jesuit scientist of the 17th century, he created the system names that are still used on the moon. His naming was displayed on a map built by his former student Francesco Maria Grimaldi.

To celebrate their hard work, Riccioli named a crater for each of them, and modestly gave the most for your student. The Riccioli crater (diameter 145 km) is striated with ejecta from the formation of the southwest Orientale impact basin. The lack of ejecta at the Grimaldi floor (230 km) shows that the lava flows that covered from spills originating from Riccioli and formed the various visible pyroclasticos deposits in these two craters erupted more recently than 3.8 billion years ago when it was formed Orientale basin. The count craters suggests that the leak of lava in Riccioli is about 3.48 billion years ago, and has Grimaldi ages of 3.25 and 2.50 billion years. The latter age of volcanic activity in Grimaldi is remarkably young.

Poren more interesting for amateur observers are the details seen in the Grimaldi floor. The large dome on the northern portion of the floor (red circle) is well known, and my image also shows some minor hills and steeper north of the great dome (yellow circle). As they appear with the sun in higher angle, these hills are more likely to be remaining parts of Orientale ejecta that were not covered by later lava. But the greatest of these hills (orange circle) is more complex - the image of Lunar Orbiter she looks like a steep dome with small hills in its northern and southern borders. On the southwestern tip of the floor there is a shadow (yellow arrow) which implies a relatively steep slope where the lava sea flowed over the crater floor. Lunar lavas had a very fluid consistency, so it is always common to find a steep slope.

The floor of Riccioli presents steep tectonic fractures that can be seen in the picture and where the volcanic lava flows streamed toward Grimaldi.

Source: LPOD- Charles Wood

            LROC / NASA

Adaptation and text: Avani Soares