The Solar System
Our solar system is an oasis of light, warmth, and life. It is home to one star, a handful of planets, more than a hundred moons, millions of rocky asteroids, billions of icy comets -- and all the known life in the universe. And it is a realm that we are still learning about as we begin to explore it in greater detail.
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ExplorationsFind out about scheduled missions to our solar system neighbors in the coming year. |
The Solar System: Inner Planets
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The Solar System: Outer Planets
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The Solar System: Minor Bodies
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The Solar System
Do all planets orbit the Sun in the same direction?
While not all of the planets rotate on their individual axes in the same direction -- Uranus and Venus both rotate opposite to the other six planets -- the planets are in agreement as to which way to go. The shared motion is an artifact of the formation of the solar system from a giant rotating gas cloud 4.5 billion years ago.
As for the reversed, or retrograde, spin of Uranus and Venus, scientists are divided as to the cause. Most subscribe to the theory that early in their histories, these worlds were subjected to massive collisions with planetary-sized objects, so powerful they reversed the planets original direction of rotation -- and in the case of Uranus, knocked it almost completely sideways.
The Astro Guides for the Solar System and Beyond the Solar System are supported by the National Aeronautics and Space Administration under Grant Nos. NNG04G131G and NAG5-13147 respectively.
The Astro Guides for the Solar System and Beyond the Solar System are supported by the National Aeronautics and Space Administration under Grant Nos. NNG04G131G and NAG5-13147, respectively.
