What is a Dyson Sphere? (Intermediate)

Hello there, I don't know exactly where I heard the term, "Dyson Sphere" but I would like to know more about it. All that I know is that it has something to do with living inside a hollow planet with a star in the middle. I would appreciate any info on the subject. Thanks!

A Dyson Sphere is a hypothetical artificial space platform which very advanced alien civilizations might construct in order to harness all of the light of their parent star. The sphere surrounds the star completely, forming a shell around it of about the radius of their home planet's orbit. Aliens live on the inside surface of this sphere, which captures all the light from the star since it surrounds it completely. That light is used for the power needs of the civilization.

Dyson Spheres are important, because they should be directly detectable from Earth as something completely different from a star, and are one of the few ways of directly indicating the existance of alien life. On the other hand, most astronomers believe that even the most advanced civilizations would find them too expensive to build.

This page was last updated June 27, 2015.

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Dave Kornreich

Dave was the founder of Ask an Astronomer. He got his PhD from Cornell in 2001 and is now an assistant professor in the Department of Physics and Physical Science at Humboldt State University in California. There he runs his own version of Ask the Astronomer. He also helps us out with the odd cosmology question.

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