Crater

Crater refers to a bowl-shaped hollow or depression found on the surface of a planet, moon, or other solid body. Craters can form in different ways, including from objects hitting the surface, explosions, or volcanic activity. They can vary greatly in size, from small pits to large circular basins stretching many kilometers across. Craters are common on the Moon and other planets because these surfaces do not have weather or water to erase them over time.

One of the most common types is the impact crater. These form when a meteorite, asteroid, or comet strikes a surface at high speed. The force of the collision pushes material outward, creating a round hole with raised edges. On Earth, many impact craters are harder to see because wind, water, plants, and geological processes can change the landscape over long periods. Some well-known craters, however, remain visible and help scientists study the early history of the planet.

Another type is the volcanic crater, which forms at the top of a volcano. When magma and gases escape from inside Earth, they can create a central opening or enlarge an existing one. These craters may fill with lava during eruptions or form lakes when water collects inside them. Volcanic craters often appear on mountains created by repeated eruptions, and their shapes can change as activity continues.

Craters also exist on planets and moons with little or no atmosphere, such as Mercury or our Moon. Because these worlds do not experience strong weather or flowing water, their surfaces display millions of craters that have stayed unchanged for billions of years. Scientists use these craters to learn about the age of a surface. Older surfaces have more craters, while younger surfaces show fewer because newer activity may have covered or replaced older marks.

Craters can provide useful clues about the past. By measuring their size and shape, researchers can estimate the force of the event that formed them. In some cases, rock and soil inside or around a crater contain melted material that formed during an impact or eruption. These clues help scientists describe ancient environments, understand geological processes, and compare Earth to other planets.

On Earth, craters can become habitats for plants and animals. Some fill with water, forming lakes that support ecosystems. Others turn into small valleys or basins that change how rainfall or rivers move through an area. Although many craters began as sudden events, they can become stable parts of the landscape and help explain how natural forces shape the surface.