EARTH 119 Study Guide - Midterm Guide: Continental Crust, Oceanic Crust, Formation And Evolution Of The Solar System

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Marked the start of the universe, space, and time. All matter and energy was initially packed into an in nitesimally small point. Universe began with only helium and hydrogen (small atoms), which accumulated into clouds called nebulae. Gravity pulled the gas of nebula into a revolving disk. The theory that the whole universe must be expanding because galaxies in every direction seem to be moving away from us. As gravitational forces began to pull mass together, stars united and grew in mass and gravity, creating nebular disks. The disks pulled in more dust and materials through gravity to form planets. As the nebula continues to contract, the temperature and pressure in the protostar increases. Once density, temperature, and pressure are high enough, nuclear fusion starts and the sun ignites. Small planetary objects that form through the action of gravity during the birth of a solar system.