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SportsCommercials t1_ja2zmyf wrote

Orbital velocity: ~8km/sec
Seconds since original launch date: ~765,849,600
Seconds at observer: ~765,849,600.27268

So to answer your question, the original section of the ISS is about a quarter of a second younger than it would be if the parts had stayed on Earth.

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Darkeyescry22 t1_ja348ma wrote

Wouldn’t this make it a quarter of a second older than it would have been? Or is the observer someone on earth?

Also, do you know the calculation for general relativity? Is that effect (from being farther from earth) near the same order of magnitude, or much smaller?

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C47man t1_ja3aq3e wrote

>Wouldn’t this make it a quarter of a second older than it would have been? Or is the observer someone on earth?

Time passes normally in the reference frame of the ISS, while Earth time goes faster. In the reference frame of Earth, the ISS ages slower. It doesn't matter which frame of reference you use.

>Also, do you know the calculation for general relativity? Is that effect (from being farther from earth) near the same order of magnitude, or much smaller?

What effect? "general relativity" is vague.

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Lashb1ade t1_ja3c41j wrote

"General relativity" would refer to time dilation due to gravity; the ISS is higher up in Earth's gravity well, so will age faster than on the Earth's surface.

I can never remember which of the two effects is larger.

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somdude04 t1_ja3f55p wrote

Moving fast is stronger. About 14 ms per year slower due to moving fast versus .3 ms per year from lower gravity at ISS orbit.

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Minovskyy t1_ja53mn3 wrote

The time dilation is not purely due to orbital velocity, there's a gravitational time dilation to take into account as well.

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