TED-Ed

Dark matter: How does it explain a star's speed? - Don Lincoln

TV-PG
2012 • E79    Nov 12, 2012    10m
All the stars in a spiral galaxy rotate around a center -- but to astronomers, the speed that each star travels wasn't making sense. Why didn't stars slow down toward the edges as expected? Don Lincoln explains how a mysterious force called dark matter is (possibly) the answer -- and why the search for an answer matters.

Where to Watch TED-Ed - 2012 • E79

 

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