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The Earth rotates around itself and revolves around the Sun. Our solar system revolves around the center of our galaxy and our galaxy is moving in some way throughout the universe. If you took into account all this, how fast would you be going just standing still? Can we even calculate such a value giving that there is no static point in the universe to which we can measure ourselves against?


marked as duplicate by Rob Jeffries, Bill N, Gert, user36790, DilithiumMatrix Nov 29 '15 at 2:23

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    $\begingroup$ Fast with respect to what? $\endgroup$ – SchrodingersCat Sep 28 '15 at 13:37
  • $\begingroup$ I'm looking for a quantifiable value. Either KM/H or MPH $\endgroup$ – Geruta Sep 28 '15 at 13:38
  • $\begingroup$ I also know that at certain times, these values would counter each other or enhance each other. So while there isn't one specific value of speed we move it, there is a range that should be able to be averaged into a generic speed. $\endgroup$ – Geruta Sep 28 '15 at 13:40
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    $\begingroup$ Perhaps you misunderstood me. Its not the unit I am talking of. There is nothing known to be in absolute rest in this universe. So we can only measure things relative to other things. So I was asking "fast relative to what?" $\endgroup$ – SchrodingersCat Sep 28 '15 at 13:41
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    $\begingroup$ Possible duplicates: physics.stackexchange.com/q/4493/2451 , physics.stackexchange.com/q/154426/2451 and links therein. $\endgroup$ – Qmechanic Sep 28 '15 at 14:33

Earth is moving around sun in an orbit with mean radius 1AU. Time of one revolution is 1 year . Thus, its speed is $$ v \approx 2 \pi \dfrac{1AU}{1year} = 30km/sec $$ Sun moves around galactic center at a speed of $ v'=220km/sec$. Thus, when you are standing still on Earth,you can have a velocity of $v'+v$ $\textit{with respect to center of Milky way galaxy}$. This value lies in the range of $[220-30,220+30] km/s$ (since velocities are added vectorially). This value is used when you can make an assumption that our galaxy is at rest.

From cosmological point of view, our galaxy is moving around other galaxies. An absolute frame of reference can be $\textit{ Cosmic background radiation}$, which is supposed to be constant throughout the space. With CMBR as reference frame, the speed of Earth measured by COBE(cosmic background explorer), is $360+/- 20 km/s$.

  • $\begingroup$ Is it safe to say then that we will never visit the same point in the universe more then once? What I mean is, if you could plot an x,y,z graph of our universe and the distance between each point was the size of one average sized human being, you would never visit the same exact point more then once because we are always moving around the earth, sun, Galaxy, and throughout the universe. $\endgroup$ – Geruta Sep 28 '15 at 13:57
  • $\begingroup$ What does "same point" mean? $\endgroup$ – WillO Sep 28 '15 at 14:02
  • $\begingroup$ @Geruta This question is not valid. Let's say you are at a point A(x,y,z) in universe at some time t1. Now, universe is expanding. After some years, that A is not a point anymore but has been stretched over to make some volume. The point I want to make is, universe is changing every sec. So, you can never return to the same point because it will not exist anymore. $\endgroup$ – seeking_infinity Sep 28 '15 at 14:04
  • $\begingroup$ @seeking_infinity: $v= \dfrac{1AU}{1year} = 30km/sec$ is a misleading formula, even though you have the right outcome. I strongly suggest to edit. $\endgroup$ – Gert Sep 28 '15 at 14:11
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    $\begingroup$ the CMB is absolutely not an absolute background $\endgroup$ – user46925 Jan 11 '16 at 13:31

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