🕰️ Time on Mars passes faster than on Earth, and it's not negligible

Time is not the same everywhere in space. On Mars, it flows on average 477 microseconds more each Earth day (24h) than on Earth, an imperceptible but real difference that originates from the laws of physics.

This singularity stems from Albert Einstein's theory of general relativity. It establishes that time is not absolute, but depends on gravity and speed. Thus, a weaker gravitational environment or a different motion alters the rhythm of clocks, an effect called time dilation (see below).


Physicists at NIST, the National Institute of Standards and Technology in the United States, performed the precise calculation of this discrepancy. To do this, they integrated the reduced gravity of Mars, 2.6 times weaker than on Earth, as well as the characteristics of its orbit around the Sun. The gravitational influence and the orbits of Earth and the Moon also come into play for the calculation of time on Earth, making the analysis particularly detailed.

In reality, these variations are notable over the course of a Martian year. Indeed, Mars's elliptical orbit causes its speed to change, slightly faster when it is closer to the Sun. All these combined parameters cause the time difference to fluctuate, potentially reaching up to 226 microseconds of offset from the average value.

On a human scale, this discrepancy seems tiny, but it has concrete consequences for future technologies. The navigation and communication networks envisioned between Earth and Mars require extremely precise synchronization. For illustration, systems like 5G require accuracy to a tenth of a microsecond, making this knowledge necessary.

This work fits into a long-term vision of space exploration. Moreover, researchers previously measured a similar discrepancy for the Moon, where time flows 56 microseconds faster. As the scientists present in The Astronomical Journal, understanding these differences prepares for establishing reliable infrastructure beyond our planet, a step towards an expanded human presence in the Solar System.

Time dilation: when the rhythm changes

Albert Einstein's theory of general relativity revolutionized our perception of time. It shows that time is not a universal constant, but can flow more or less quickly depending on conditions. This effect, called time dilation, occurs under the influence of two main factors: gravity and speed.

In an intense gravitational field, such as near a black hole, time slows down relative to a place where gravity is weak. Similarly, an object moving at a speed close to that of light will have its clocks tick slower. These phenomena are not just theoretical; they are confirmed by experiments and precise observations.

On Mars, gravity is weaker than on Earth, which tends to accelerate its proper time. Nevertheless, the planet's orbit adds a component of variable speed. When Mars is closer to the Sun, it moves faster, which has an opposing effect.

This understanding is fundamental to modern physics. It allows for the interpretation of cosmological observations and the development of advanced technologies. Ultimately, time dilation reminds us that our perception of time is linked to our environment and our movement in the cosmos.