NASA/JPL-Caltech/ASU/MSSS
How long is time on Mars? Physicists have measured for the first time, with great precision, how time passes on the Red Planet, by calculating the difference between a Martian atomic clock and a terrestrial one.
A group of physicists from the National Institute of Standards and Technology (NIST), in the United States, has just calculated with a unprecedented precision the way time passes on Mars compared to Earth, a step considered essential for any future program of permanent human presence on the Red Planet.
Using the time dilation formula from the theory of relativity, the team analyzed in detail the movement of Mars and the effect of its gravity on atomic clocks, and concluded, in a study published in The Astronomical Journal, that a clock placed on the surface of Mars would advance, on average, 477 microseconds per day compared to an identical clock on Earth. A microsecond corresponds to a millionth of a second, but these deviations accumulate over time.
The value, however, is not constant, it highlights the . Due to Mars’ eccentric orbit, the daily difference can vary by up to 226 microseconds, depending on the planet’s position in its trajectory around the Sun. This is more or less what happens on the Moon: recent studies have estimated that, on Earth’s natural satellite, clocks move forward by around 56 microseconds per day, in a much more stable way, thanks to the almost circular orbits of the Moon around the Earth and the Earth around the Sun.
In the case of Mars, this does not happen. The distance to the Sun and the eccentric orbit make variations in time greater. “One is already extremely complicated. Now we are dealing with four: the Sun, the Earth, the Moon and Mars”, explained NIST physicist Bijunath Patla, quoted in .
To reach the results, the researchers had to simultaneously consider the gravity on the surface of Mars, its elongated orbit and also the gravitational effects of the Sun, the Earth and even the Moon. The objective is to anticipate what adjustments are necessary to keep clocks and navigation systems synchronized between the two planets.
Future navigation systems on Mars, like Earth’s GPS, will rely on extremely accurate clocks, the rates of which are affected as described by Einstein’s general theory of relativity. In practice, this means that a person would age slightly faster on Mars: After 50 years on the neighboring planet, it would be about 9 seconds older than if it had remained on Earth.
