In a few weeks, most Americans will have to switch their clocks back one hour as daylight saving time ends and switches to ...

Daylight saving time became a national standard in 1966 when President Lyndon B. Johnson signed the Uniform Time Act, which ...

How do we know the time... precisely? The question is more complex than it first appears, says Richard Fisher.

How do we know the time... precisely? The question is more complex than it first appears, says Richard Fisher.

The tick of the world clock depends on hundreds of atomic oscillators positioned across the globe.

Does the moon have its own timezone? How do we tell time there? Scientists want to create a standardized lunar clock, but it’s complicated.

Satellite navigation systems for lunar settlements will require local atomic clocks. Researchers are figuring out what time they will keep.

Even guardians of America's atomic clocks say time doesn't work the way we think it does.