Time really does move faster on Mars, but the breakthrough that confirms it did not come from a spacecraft’s stopwatch.

On Earth, knowing the time feels simple. Your phone pings the same second as a GPS satellite and an atomic clock in a lab. Everything is wired together so well that you rarely think about the ...

Breakthroughs, discoveries, and DIY tips sent every weekday. Terms of Service and Privacy Policy. Tracking the first astronauts’ visit to Mars won’t be as simple ...

Off Earth, identical atomic clocks won’t agree; gravity, motion and relativity make time flow differently, so Earth and Mars ...