The dictionary definition of the word crater is as follows “a large hole in the ground or a surface caused by an explosion”. These holes or craters can either be manmade or can be natural. Basically a crater is a deep hole found on the moon or any planet surface. Impact crater is generally referred term when the word crater is used.
When a planetary object or a large body of a planet collides at a high velocity with a small projectile it causes an impact crater. The craters that are caused due to the meteorites are known as the meteorite craters. The size of a crater varies from very large, multi ringed basin to a small simple hole in the ground. The craters that are very big in size have lava filled in them and only their outlines can be seen.
When something collides with the surface of the moon and makes holes craters are formed on the surface of the moon. Asteroids and meteorite collision is the main reason for the formation of craters on the surface of the moon. Usually the asteroids and meteorites strike the surface of the moon at 20 km per sec or 12 mile per sec. The craters like moon and other planets are also found on the surface of our planet earth but comparatively are lesser than the moon. The reason behind this is that most of the asteroids and the meteoroids that are the major cause of these craters are burned up in the earth’s atmosphere. Since moon has no atmosphere thus there is more collision on the moon surface and thus moon has more craters. The craters on the moon surface stay in the same shape for a longer period of time until a new object collides because unlike earth factors such as wind, rain, erosion etc are not present on the moon.
The shape and size of the craters found on the surface of the moon depends mainly upon the angle of the object that collides with the surface, its size, its speed and above all it’s mass, so we can say that the craters can be of any shape or size. When big objects strike the moon’s surface at a very high speed these result in the formation of huge complex craters and new craters are formed when the ejected object again falls on the moon surface.
Other then the impact craters there is another form of craters known as the volcanic craters. These volcanic craters have been found on Jupiter’s moon, Mars, Venus, Earth’s moon and Earth. Due to the collapse of a part of a volcano or the build-up of lava which is the erupted volcanic deposit the volcanic craters are formed. Even though in most of the cases the craters are formed as a result of meteor collision, some are formed as a result of volcanic activity. Crater lakes are formed the craters caused by the volcanic activity are filled with rain water or melted snow.