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Speed of Light

The maximum velocity for everything in the universe; 186,282.397 miles (299,792.458 km) per second, or fast enough to go to the Moon and back in less than three seconds.

Radio Programs

Night Watch Picturing the distant stars April 3, 2016

Moon and Spica The end of a long journey February 26, 2016

More Moon and Companions Turning on some far-away lamps June 26, 2012