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Do you know what time it is? It's an easy question, right? Just look at your phone or watch. But is that really the exact time? Oh, well, for that you can look to Coordinated Universal Time, or UTC. It's what your phone clock is synced to, give or take, but you can get a more accurate measure of UTC with a device that can pick up the UTC radio time signal. Of course, UTC is only an agreed-upon standard that tries to stay in sync with Earth's rotation. It, in turn, is based upon International Atomic Time (TAI), which is a weighted average of 450 atomic clocks located all over the world.

