When an asteroid hits, the energy released by the impact depends on a great deal of factors, from the size of the asteroid and the materials it is made of, to speed and the angle of the strike. In any case, the effects of such events are devastating, and often leave deep scars on the surface of celestial bodies.
Most of us imagine these scars, which eventually, hundreds of years after they’ve occurred, shrink down to the impact crater itself, as very chaotic areas, with no apparent rules to guide their appearance. But, as seen in the image we have here, that’s not always the case.
The bowl in the ground you’re looking at now is the Martian Cassini Crater (there’s another one called the same on the Moon). Named so in honor of Italian astronomer Giovanni Cassini, it formed violently at an undetermined time in the planet’s past, and it’s huge by any standards, measuring 415 km (258 miles) in diameter - for perspective consider the largest known crater here on Earth, Vredefort, had a diameter of at most 300 km (186 miles) when it formed, and the one resulting from the impact that wiped out the dinosaurs was half that.
Almost perfectly preserved by the uneventful planet, the crater looks incredibly smooth inside in the photo taken by the HiRISE camera from an altitude of 290 km (180 miles).
The smoothness of the place was probably caused by the winds that blow on Mars, which had more than enough time to pacify the place, or on account of the crater being the place where long ago a lake may have existed. It if did, then it would have been larger than the Baikal, our planet’s largest lake by volume.