Apart from planets, stars and moons, there are several small solar system bodies such as asteroids and comets in space. These are usually speeding through space. Sometimes, a larger body such as a planet or a moon can come in their way. When this happens, these extremely fast spacebodies crash into the surface of the larger space body and create a depression called impact crater.
For an object to be able to create an impact crater, it needs to be travelling at a speed of many thousand kilometres per hour. No matter how hard or tough the surface of a planet or the moon is, when a superfast object collides with it, it will definitely leave an impact by vaporizing the area and creating enormous shockwaves through the ground, which can melt and recrystallise rock.
The size and shape of a crater depends on factors such as mass, density and velocity of the impacting object, and the geology and velocity of the impacting object, and the geology of the surface it strikes. Many planets and moons in our solar system have impact craters.
Two of the famous impact craters on Earth are:
Meteor Crater
Also known as the Barringer Crater in Arizona, the U.S., this is the first crater formed by an extraterrestrial impact to be identified. It formed nearly 50,000 years ago from a meteorite that may have been up to about 150 feet wide travelling at more than 45,000 kmph.
Vredefort crater
Situated in South Africa, this is the largest-known impact crater on Earth. It is nearly 300 km in diameter and over two billion years old. However, due to erosion over time, it is difficult to see the crater. What remains today are geological structures at its centre known as the Vredefort Dome or Vredefort impact structure.
Picture Credit : Google