# Combined speed of Earth in Space is 1.5 million mph - how much slower is time for Earthlings as a result?

Theres a problem for intergalactic astronauts which is finding their way back to Earth. Combining all the rotational speeds, we are spinning and orbiting the sun, in our solar system which is spinning in the Milky Way, which is spinning in a large cluster, which in turn spins in a super cluster. Combining all the speed of the rotational forces equals 1.5 million mph. Said Intergalactic Astronaut would have a job to find where the Earth is if they flew into space and out of the super cluster. But my question is this, the astronaut HAS managed to find a ship to leave the Earth, the solar system, the Milky Way, the Large cluster, the Super cluster and is at relative to us, is motionless in space, observing us. How much faster is time for the astronaut? Or how much slower is time for us on Earth, given the speed of Earth and gravitational effect on time.

-
1.5M miles/hr relative to what exactly? There is no such thing as absolute speed. Every speed is relative to something. – Pranav Hosangadi Dec 2 '13 at 19:34
There is no such thing as "motionless in space" without a reference. Motionless compared to what? – Olin Lathrop Dec 2 '13 at 20:52

the astronaut [...] relative to us, is motionless in space, observing us

I think what you mean is that the astronaut is in the same frame-of-reference as the centre of the 'super cluster'. If the astronaut was motionless relative to us then she/he would experience/measure the same flow of time as us. You should note that the commonality between Galilean and `Einsteinian' relativity is that there is there is no single absolute 'frame' in which speed can be measured relative to - even empty space!

If the astronaut was at the centre of the super cluster structure that you're referring to then you might expect the relative time dilation factor to be ~1.0000025.

-
I'm applying the theory of a balloonist and a person on a carousel. The Baloonist (astronaut) hovers above the carousel rider (Person on Earth). The astronaut is vertically above the plane of our solar system "hovering" above the sun watching the persons on Earth. Therefore the Astronaut is not rotating at speed (on Earth) not orbiting the Sun at Speed. The astronaut keeps going up - above the centre of the Milky Way, above the centre of the large and super clusters, therefore escaping the rotational speeds of each. Does it make time differ for them compared to someone on Earth. – user34136 Dec 7 '13 at 10:26