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Avani Soares

Location of Photo:

Parsec Observatory, Canoas, Brazil

Date/Time of photo:

December, 29-2022; 22:08 TU


C14 Edge + ASI 290MM + IR Pass 685


When I see Theophilus, Cyrillus and Catharina well positioned in relation to the terminator, I can't help but shoot a few frames. Theophilus is a spectacular formation with all the complexities inherent in a Tycho-class crater: terraced walls, flat floor and magnificent central mountain peaks. It is 96 km in diameter, and the drop of the highest mountains from the rim to the floor below is 4.3 km, imagine an observer on top of the mountain looking down on the floor below, it must be breathtaking! Observers have reported that the shape of the central mountain appears to change as the lunation progresses, it must be due to shadow play, even so, keep an eye out for Theophilus in upcoming lunations and see if you agree. Notice how Theophilus's floor is much smoother than Cirillus's and Catharina's. When the impact that produced Theophilus occurred, much of the excavated material shot upwards. When it came back (in the form of molten rocks and boulders the size of mountains), it oozed down the smooth floor in the form of lava. There is also impact melt around the outside of the crater (arrow 1) that can easily be seen with backyard telescopes. Take advantage of this, as there aren't many places on the Moon where you can see such a thing. Most of this impact melt occurs northeast of the crater and flows into Sinus Asperitatis. Lunar scientist Charles Wood points out that this is because the south rim is higher. Shortly after the impact, the terraces located to the southwest (arrow 3) collapsed into the lake of molten lava below, see the triangular block that slipped downwards similar to the one found in the Plato crater (arrow 2) . Do not forget that these terraces were more than 4 km high, imagine this colossal amount of rubble falling on the molten lava, this formed gigantic waves of hot lava rushing towards the opposite side. As the north rim is lower, these waves crashed against the wall, rose its edges, overflowed to the outside of the crater and accumulated to the northeast as can very well be seen and indicated by arrows 1. Why does this area attract so much interest from observers? Perhaps because it includes the second best visible crater on the Moon (after Copernicus). This means that the entire interior of Teophilus crater is clearly visible, with its wide flat floor and huge central mountains. The second reason that makes this area one of the favorite targets is that there are three craters there, Teophilus, Cyrilus and Catarina. These three craters are approximately 100 kilometers in diameter and illustrate different stages of degradation. Cyrilus crater is older than Theophilus crater as it is noted that its rim was modified by the impact that formed Theophilus. Catharina crater is certainly the oldest of the 3, both because it is more worn out and because it has been modified by several later impact craters, and a large crater can even be seen on its northern edge, in addition to being much shallower than the others. which means it was probably filled with ejecta from the Imbrium Basin. Perhaps there are additional reasons to make this a privileged spot for observation, a sea, a flooded basin cut by mountain ranges and 3 magnificent craters. When you observe a lunar region and are aware of all these factors, you will certainly see the Moon with different eyes! Text and adaptation: Avani Soares