Oceans have a major effect on climate, because water in the oceans hold a large amount of heat. Living have played many roles in the Earth system, including affecting the composition of the atmosphere and contributing to the weathering of rocks. Changes are constantly occurring in and on the earth. The Earth processes we see today, including erosion, movement of crustal plates, and changes in atmospheric composition, are similar to those that occurred in the past. Earth history is also influenced by occasional catastrophes, such as the impact of an asteroid or comet.
Fossils provide important evidence of how life and environmental conditions have changed.
Changes are constantly occurring in and on the earth. The Earth is the third planet from the sun in a system that includes the moon, the sun, eight other planets and their moons, and smaller objects such as asteroids and comets. The sun, an average star, is the central and largest body in the solar system. Most objects in the solar system are in regular and predictable motion. These motions explain such phenomena as the day, the year, phases of the moon, and eclipses.