The MRO spacecraft photographed seven holes in the ground in different places on Mars, apparently the entrances of huge caves
NASA's Mars Reconnaissance Orbiter (MRO) recently took some pictures of mysterious cave openings on Mars.
The dark spot in the center of the image is probably a hole in the middle of a smooth lava landscape. This is not an impact crater because there is no basin surrounding it and there is no trace of material ejected from the ground. The sunlight apparently manages to get in, but the hole is so deep that it doesn't come back out, it's just a dark hole.
The scientists estimate that this is a cave whose ceiling has collapsed or a hole with particularly steep walls. In any case, these are surprising objects. In any case, this is not an anomaly, so far seven such sites have been discovered on Mars.
incidentally, On the website of the Planetary Society, it was reported that the diameter of the hole in the picture is about one hundred meters.