When astronauts head to Mars, they will experience time dilation. That’s to be expected. In fact, your feet and your head experience time dilation, with your head aging ever so slightly faster than your feet. But how much time dilation will they experience (relative to Earth observers)?
First off, let’s check we’re all on the same page. Time passes at different rates for different observers, depending on their relative speeds, and their proximity to (and strength of) nearby gravitational fields. Time dilation is the difference between time elapsed on two clocks due to these causes, as described by special relativity and general relativity.
Gravity
The further you get away from Earth’s gravity – say, by working at the top of a skyscraper – the more pronounced the time dilation effect (compared to observers on the ground). It’s not a huge effect, measuring just a tiny
For astronauts and cosmonauts living in zero-gravity environments for long stretches, the effect is more pronounced, but effectively canceled out by the speed at which spacefarers tend to travel.
“Because astronauts and satellites orbiting the Earth are slightly further away from the centre of the planet (compared to people on the ground) they actually experience less gravitational time dilation. On its own this would mean astronauts’ time would run faster,” astronomer Colin Stuart explained for
When cosmonaut Sergei Krikalev became
Heading to Mars on a 21-month round trip, astronauts will experience small amounts of time dilation. From their point of view, time will pass normally – while compared to Earth observers, there will likely be a few nanoseconds difference. Though the speeds will be faster than any human has traveled in history, in comparison to light speed – where time dilation effects get
If astronauts are to stay on Mars for extended periods of time, then the effect of gravitational time dilation gets within the realms of noticeable. According to The
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