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Observing the Sky Solar System Satellites Navy Research Resources

Our Solar System

A solar sytem is a collection of planets and other objects orbiting a central star, or stars. At the center of our solar system is the familiar Sun, orbitted by nine planets and many moons, asteroids, and comets.

Diagram of our Solar System

Our solar system started out as a large cloud of gas and dust. No star, no planets, but all of the basic ingredients needed to make them. About 4.5 billion years ago, something disturbed that cloud and it began to collapse. Clumps of gas and dust were pulled together by their mutual gravitational attractions, and the center of the cloud grew so hot and dense, it ignited into a star.


The rest of the original cloud spun around the new Sun as clumps of gas and dust formed into planets and moons. Powerful energy flowing out from the Sun heated up the space around it, and determined the characteristics of the new planets.
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