# Is time passing really differs on other planets/in interstellar? [duplicate]

I am aware of the idea of time dilation (which I, by the way, asked another question about) on speeds, that get close to the speed of light. Though, I wonder what other (if any) forces and laws affect time passing on other planets and in interstellar.

The following thought experiment might illustrate (at least I hope it will) what I am asking:

Say we have 10 clocks that run forever (i.e. they do not require rewinding at all), are perfectly synchronized and are not damaged by any external conditions on other planets (high temperatures, acids etc.). Now let's assume we have put a clock on the surface of each planet in our Solar System (i.e. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto). Let us also assume that we never approached speed of light while transporting the clocks (say we used space bicycle, or something :-). The 10-th clock — we just released it (somewhere behind the Pluto, perhaps) to drift into interstellar space. Then we came back to Earth and waited (according to the clock we left on Earth) for exactly 1000 hours.

1. Assuming that nothing would cause clock in interstellar to move close to the speed of light, what time will be displayed on each of the clocks (given we could, somehow, check it simultaneously)?

2. Would the results differ if we were able to synchronize all the clocks, exactly at the moment we started counting our 1000 hours from?

• Hi Filipp. The duplicate I've suggested above specifically refers to Mars but the answer applies to all planets. Commented Nov 18, 2018 at 15:50
• Thanks, @JohnRennie, read&upvoted =). What about interstellar space? Would it be the same, but omitting the 3-rd step of ΔΦ calculation (i.e. addition of the (negative) potential energy change to descend to the surface of the planet)?
– user187075
Commented Nov 24, 2018 at 8:23
• Yes. You'd consider only the potential energy change moving in to the orbital radius then down onto the surface of the planet. Commented Nov 24, 2018 at 9:29