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Photograph provided courtesy of Steve Albers

Sound Waves vs. Light Waves

You see a flash of lightning across the night sky. Five seconds later, your hear the rumble of thunder. If lightning and thunder come from the same source, then why don't they occur at the same time?

Actually, they do occur at the same time. The difference is due to the way sound and light travel. Light travels extremely fast. In fact, it is faster than anything else. Sound travels pretty slow. That is why we can see light in an instant, but it takes a while to hear thunder.


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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF