Einstein was right: Time ticks faster on Mars, posing new challenges for future missions

Astrophysics and gravity are fascinating topics, and Albert Einstein's genius has once again been proven! Time moves differently based on the gravity of planets.

 ( IMAGE: Time moves slightly differently on Earth and Mars due to the two planets' differing gravitational pulls. A new study confirms this prediction of Einstein's relativity. (Image credit: NASA/JPL)

Einstein was right: Time ticks faster on Mars, posing new challenges for future missions

LIVE SCIENCE, By Deepa Jain, Dec. 11, 2025

Clocks on Mars tick faster by about 477 microseconds each Earth day, a new study suggests. This difference is significantly more than that for our moon, posing potential challenges for future crewed missions.

Scientists have found that time moves slightly faster on the Red Planet than it does on Earth. Clocks on Mars tick, on average, 0.477 milliseconds (477 microseconds) faster over 24 hours when measured from Earth compared with time recorded on our planet, a new study finds. Knowing this difference may help in establishing an "internet" across the solar system.

Over the next few decades, humanity's presence in the solar system is set to boom, with missions like those in NASA's Artemis program expected to pave the way for permanent settlements on the moon and beyond. Developing a standard clock for each cosmic locale would help astronauts navigate these worlds while coordinating communications with Earth.

But there's a catch: Time doesn't run at the same pace everywhere. Albert Einstein's theory of general relativity shows that time in a given area depends on how strong the gravity is there. Clocks in areas of high gravity tick more slowly than those where gravity is weaker, which is why people residing atop mountains age a fraction of a millisecond faster than sea-level dwellers. (Time appears to move faster at high altitudes, where Earth's gravitational tug is reduced.)

A trio of comets, a mysterious glow at the center of our Milky Way galaxy, why time moves faster as we age, and whether we should bring back Neanderthals. Additionally, time on a planet depends on its velocity around its parent star; the faster the orbital rate, the faster the passage of time.

Time keeps on slippin' 

Together, velocity and gravity cause time on different solar system bodies to tick at different rates when measured from Earth. A 2024 study calculated that clocks on the moon would run an average of 56 microseconds (millionths of a second) faster than Earth-based ones. Having established this, the researchers — Neil Ashby and Bijunath Patla, both physicists at the National Institute of Standards and Technology in Boulder, Colorado — turned their attention to Mars.

First, they chose a reference level on Mars — an equivalent to Earth's sea level called the areoid. Then, they used physics-based formulas to calculate how, at the areoid, Mars' and Earth's gravities and velocities would influence Martian time. Although Mars' slower orbital speed relative to Earth slows down Mars-based clocks, the planet's weaker surface gravity — five times lesser at the areoid than Earth's sea-level gravity — speeds them up much more.

(IMAGE: A gravity map of Mars taken by NASA's Mars Global Surveyor (MGS). For the new study, researchers had to find a region of Mars akin to Earth's sea level, then compare the gravity and velocity of the region with Earth. (Image credit: NASA/JPL)

But this analysis neglected the orbits' shapes. Mars' orbit is more egg-shaped than Earth's, having been contorted by the gravitational tugs of Earth and its moon. (Mars' moons, Deimos and Phobos, have a negligible impact, Patla told Live Science in an email, because of their puny size. They're just a few miles wide, compared with 2,159 miles, or 3,475 kilometers, for Earth's moon.) So, Ashby and Patla factored Mars' orbital shape, the sun's gravity and Earth moon's gravity into their equations.