[midasuni]

Nothing in the solar system has a relative speed different enough to earth to make common timestamps different - the difference is well below leap second impacts.

As for simultaneity we already have to deal with that at the millisecond level. An event logged at 16:00:01.000 as far as LA is concerned maybe logged at 16:00:01.080 in London, or maybe at 16:00:00.920

[contravariant]

I mean the clocks on different planets do tick at slightly rates. It's somewhere on the order of milliseconds per year, except for really large planets, but it does add up

[midasuni]

Yea, same as clocks in orbiting satellites, or even difference in rates between different locations on earth.

The difference is negligible compared to leap seconds.