The shadow-cast image of the Moon crater Cassini is not only captivating but a reminder of how the lunar Alpine Valley is so geologically interesting. There are several notable moon crater names with unique & plain features that present themselves in this one telescopic view—all with different stories or theories of how they came to be as we observe them on the lunar landscape. Some of which are still a mystery to this very day.
Nevertheless, It is quite a sight on a clear evening observing and imaging the new dawn creeping down Plato’s slopes through a 5″ scope. So much to see in such a small point of reference.
All in one view, the brooding Plato, the mysterious & anomalous crater Cassini, the famous Alpine valley, and the glorious Mons Piton dominating the surrounding maria can be seen.
The graphic above indicates the locations of some of the more prominent features of interest in this area.
First, indicated in the upper left of the graphic, lies an excellent and plain example of an otherwise typically very discreet lunar feature, the lava flow front, otherwise known as a “lobate flow” or lava scarp. The leading edge of an ancient massive lunar magma flow, which worked its way across the maria over 3 billion years ago, is here frozen in time.
The utter ferocity of the gigantic Imbrium impact, which formed the Imbrium basin wherein Mare Imbrium lies, is witnessed here as well, its ejecta plowing through the lunar Alps like a giant comb.
Untouched by this catastrophic impact is Lower-Imbrium Cassini, a very odd crater indeed. No one really knows for certain in what manner Cassini came to appear the way it does today, unusually shallow, filled with lava and surrounded by an uncharacteristicly lobate and almost pristine looking ejecta “skirt”.
One of the posited explanations for this unusual surround is that Cassini impacted into either still warm or even a still molten layer of fresh maria inside the newly formed Imbrium basin, landing with more of a splash, than a thud. mysterious
Near Cassini is a little ‘galaxy-like’ looking feature in an area which, along with other nearby protuberances like Mons Piton, are exposed peaks from another age, a remnant from the Imbrium impact, or perhaps from impacts that occurred shortly after the basin was formed.
It is still visible standing above the younger lavas, which subsequently flooded the giant impact basin during the upper Imbrium period, making these peaks islands in a rocky sea.
Our lunar ‘galaxy’ owes its brightness to the fresh Copernican craterlet that smacked into the middle of this hilly area sometime within a billion or so years ago, frosting the hills with its bright, fresh ejecta. A time-lapse camera would have been safe, refuged on this high ground, to record the entire history of the flooding of the Imbrium basin and the creation of Mare Imbrium.
Ghost craters are always fascinating, realizing they are some of the earliest impacts still faintly visible today. One is outlined on the graphic, as big as Plato itself. Where Plato impacted in the uplands, edging the Imbrium basin and escaping being inundated by mare lavas is thus preserved for us to view today.
The old ghost adjacent to it appears to have formed at a lower elevation, placing it inside the basin, which would account for its almost complete burial under the mare lavas, which later flowed freely here.
It is always a spectacular trip traveling via scope through the Lunar Alpine Valley, experiencing the Cassini crater in Plato country.
