How fast does light travel?

The speed of light in a vacuum is 186,282 miles per second (299,792 kilometers per second), and in theory nothing can travel faster than light. In miles per hour, light speed is, well, a lot: about 670,616,629 mph.

A traveler, moving at the speed of light, would go around the Earth 7.5 times in one second. By comparison, a traveler in a jet aircraft, moving at a ground speed of 500 mph, would cross the continental United States once in 4 hours.

More Info: www.space.com

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37 Comments

Rgd

In my experience, people complain about grammatical errors when they feel inferior. That means they are pissed they got the question wrong, so now it’s time to attack the messenger. It’s an old ploy used by the progressives when they can’t win an argument. Come on people, have fun and lighten up!

Louise C.

Did not get this one and I am ashamed of myself, but hopefully I shall remember this one.

Karin Johansson

Jeff Carter, you are a minority.

Richard S. Levine

Rgd, RIGHT ON! They also use politics, inappropriately!!

Diana Newman

Great information

Kathryn Cavanagh

Wild stab at this, had no idea..!! MISSED it.!!

Richard Hoff

Even though most of the world is metric doesn't mean that we shouldn't know Imperial or US weights and measures.

Keith Richard Mears

Although I grew up in an era of imperial measurement & understand the conversions, it would have been helpful to those brought up in a totally metric system to have had the conversion stated beforehand in the answer choices.

Sylvia Joyce Richards

Bill Knott, I do, in 50's early 60s was taught imperial measurements, then metric arrived, still use miles in UK as well as Kms.

Bill Knott

really? Miles per second? Who uses miles anymore?

Andy Fobear

The speed of light is the speed of causality. It is the minimum time of observation. All massless particles travel at the speed of light and only the speed of light. (Light) photons, gravitational waves and gluons are massless and travel only at "C". The Lorentz transformation predicts the cosmic speed limit. "C" is a fundamental value in physics.

David Gregory

How about when it goes around corners !

Andy Fobear

Kendavis, I am curious what your reference to a black hole has to do with the internationally agreed-upon speed limit of 300 thousand meters per second for photons. There are other particles and waves that also seem to observe this Cosmic speed limit. I ask because I truly enjoy learning and science so if there is a scenario where a black hole supersedes this limit I would like to understand it. I am aware of Hawking radiation and gravitational waves, but as far as I understand these still play by the rules governed by traditional Newtonian and Einsteinian laws of motion.