Strange Ina
Perhaps the most surprising images of the lunar surface provided by the LRO spacecraft capture a peculiar structure known as Ina. The small depression in the Lake of Happiness, with a diameter of 2.9 km and a depth of only 30 meters, is unlike anything we have known from the Moon before. Apollo 15 astronauts discovered it already in 1971 from the body’s orbit, but it was only in the images from LRO that its peculiarity was shown in its full beauty.
In shape, the unusual formation resembles a slice of a tangerine rather than a lunar crater and must have been created during volcanic processes. Less certain is when this occurred. There are only two impact craters with a diameter of more than 30 m on the 8 km² of lava filling there, which indicates that the local surface is very young and the bombardment with small meteoroids has not yet been enough to reshape it. According to the number of impacts, Ina could have been formed 100 million years ago, from a geological point of view recently. This would be the youngest manifestation of the Moon’s internal activity, much younger than scientists previously thought.
However, leading American planetologists hold a different opinion Lionel Wilson a James Head. According to them, the slight age of the formation may be related to the special structure of volcanic rocks in the form of extreme foaming of lava, the so-called lava foam. If such a structure were located in the Ina area, it would soften the impacts of cosmic bodies – and much smaller impact craters would be created than those that would form during the same collisions in other lunar locations. The subsoil there can thus significantly distort and underestimate the age of Ina. The authors of the study mention that the area could even be as old as other volcanic formations, or at least two billion years. (Photo: Wikimedia Commons, NASA, PDM 1.0)
Fascinating details of Aristarchus
If you’ve ever looked at a photo of a full moon, you’ve probably noticed an unusually bright crater Aristarchus with a diameter of 40 km. No wonder, because its bottom is one of the brightest areas on the Moon. Geologists agree that this is one of the most amazing places on the surface of our neighbor. The interestingness of the location is also indicated by the fact that it was shortlisted for the landing of future Apollo missions, which, however, did not take place due to the shortening of the program.
The mosaic of images from the LRO probe capturing the bottom of the crater speaks of extremely complicated phenomena that took place in fractions of seconds during the impacts. Scientists have not yet fully understood many of the mentioned processes, because they have not yet had the opportunity to observe the course of impacts of such dimensions.
In the composite shot, the amount of debris thrown up and falling back is visible on the bottom with a depth of up to 2,700 m. The uneven surface is also marked by countless zigzag cracks, which are traces of the flow of rocks melted during the impact. A 300 m high central peak emerges from the bottom, which was pushed out of the underlying layers by the impact. (Photo: NASA/GSFC/Arizona State University, CC BY-SA 4.0)
Bright glaze of moon seas
One of the biggest mysteries of the lunar surface is hidden by the strange bright spots in the lunar seas. Their most well-known representative became the formation referred to as Reiner Gamma, which is located on the far side of the body, so we can comfortably observe it even with small astronomical telescopes. The oval spot with a diameter of 73 km is captured by a mosaic of images from the LRO probe.
We find only five locations on our companion where these strange spots are clearly visible. Although these are very striking formations, they have no relief. It looks like someone mixed a light glaze into the ancient slurry of molten dark lava that formed the moon sea. Scientists have been searching for an answer to the question of how the mentioned spots came about and why they are only visible in a few places on the lunar surface for over half a century. Of particular importance was the finding that all of them are located in regions of magnetic anomalies.
The Moon does not have a global magnetic field, but it does exhibit local variations that persist for unknown reasons. According to some experts, the impacts of cometary nuclei, whose tail with ionized gases modified the magnetic properties of some lunar regions, are responsible for them. These anomalies could then change the susceptibility of the surface to weathering, which causes the material to gradually darken – which is probably why the spots are so light. (Photo: NASA/GSFC/Arizona State University, CC BY-SA 4.0)
The “instant” mountains of Tycho Crater
Among the most striking and impressive formations on the far side of the Moon is undoubtedly the crater Tycho with a diameter of 85 km, which is a typical representative of the so-called complex craters: It has a terrace-like gradation of internal ramparts and a relatively flat bottom with a depth of approximately 4,800 meters. It is one of only a few lunar formations for which we know the absolute age. Thanks to radiometric dating, we know that it was created 109 million years ago, i.e. at the time when dinosaurs roamed the Earth. However, this is quite recent in terms of lunar evolution, and Tycho thus represents one of the best-preserved traces of a cosmic catastrophe of this magnitude.
At its bottom there is a striking group of central peaks rising to a height of 2 km. At the same time, the aforementioned high mountains grew immediately after the impact in just a few minutes! (Photo: NASA/GSFC/Arizona State University/LRO, CC BY-SA 4.0)
A novice among the baptized
There aren’t many lunar craters named after women: Of the more than 1,600 currently named features of this type, only 32 bear a female name. At the same time, there aren’t many craters on the Moon that were named only recently. However, the ten-kilometer giant on the far side of our companion fulfills both. The International Astronomical Union gave it a name in 2015 Pierazzoaccording to a prominent Italian planetary scientist Elisabetta Pierazzo.
The crater has become a model example of an impact structure, which is lined with dark radial rays of rocks melted by the impact of the body. However, determining its age is complicated by the fact that there are a number of smaller craters on the ramparts and slopes there. It is not clear whether they arose as impacts over millions of years on the original formation, or were formed during the impact of debris from the Pierazzo crater. (Photo: NASA/GSFC/Arizona State University, CC BY-SA 4.0)
Giant peaks without a name
About 4.3 billion years ago, an asteroid hit the Moon and carved out the largest known impact basin in the Solar System. His name is South Pole – Aitkenwhile it has a diameter of 2,500 km, which corresponds to almost two-thirds of the lunar diameter, and a depth of only about 13 km.
We will never see the given structure from Earth, as it is located on the far side of our companion. Images from the LRO probe, however, show us in unprecedented detail and completely unknown views. A mountain bearing an unofficial name Malapert is considered a remnant of the South Pole edge – Aitken. The peak at lower left is one of the candidate areas considered for the Artemis III landing. The image covers an area roughly 25 kilometers wide. (Photo: NASA/GSFC/Arizona State University, CC BY-SA 4.0)
Dark Rays of Hell Q Crater
A small crater Hell Q with a diameter of 3.4 km, it belongs to the younger tracks after the impacts of bodies on the lunar surface. That is why we can observe a number of details in it that have already been obliterated by erosion in its older counterparts. Very interesting are, for example, the rays of dark material extending away from the formation. It is undoubtedly an impact melt, i.e. the material of the bedrock, which melted at enormous temperatures and pressures during the impact and was catapulted into the wider area. The substance then quickly solidified into a glassy substance that strongly absorbs light and therefore appears darker than the surrounding surface. (Photo: NASA/GSFC/Arizona State University, CC BY-SA 4.0)
2023-12-30 23:10:55
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