I think this isn't answerable without having point of reference from which speed at which earth travels in space, however if I am wrong the please give absolute distance.
Considering that earth spins around it's axis and around the sun and solar system rotates around centre of the galaxy.

The circumference of the Earth at the equator is 25,000 miles. The Earth rotates in about 24 hours. Therefore, if you were to hang above the surface of the Earth at the equator without moving, you would see 25,000 miles pass by in 24 hours, at a speed of 25000/24 or just over 1000 miles per hour.

Earth is also moving around the Sun at about 67,000 miles per hour.

Using speed measurements of the gas at different distances from the Galactic centre, the Sun appears to be cruising along at 200 kilometres per second and it takes 240 million years to complete the grand circuit around the Galaxy.

I am not sure if it's ok to just add numbers or some formula should be used since all the movements are rotational.

If average person lives 80 years, what distance does one travels in his lifetime?

EDIT: Point of reference should be centre of our galaxy, unless you believe there is better point of reference possible.
EDIT2: Is this correct calculation or am I missing something.

1000 mph = 447.04 m/s, 67000 mph = 29951.68 m/s
447.04+29951.68 + 200000 = 230398.72 m/s
80 years = 2.52455e9 seconds
230398.72 m/s * 2.52455e9 seconds = 5.8165309e+14 meters
5.8165309e+14 metres = 3888.11076 Astronomical Units OR 0.0614820933 Light Years.

Edit3: Following answer from @Johannes

371000 m/s * 2.52455e9 seconds = 9.3660805e+14 metres
9.3660805e+14 metres = 6260.83811 Astronomical Units OR 0.0990016635 Light Years.

Edit4: I just realised that I need to add all 4 (earth rotation + rotation around sun + rotation around galaxy + and galactic cluster movement speed relative to CMB).

5.8165309e+14 meters + 9.3660805e+14 metres = 1.5182611e+15 metres
1.5182611e+15 metres = 10148.9489 Astronomical Units = 0.160483757 Light Years

One travels ~16% of light year in a lifetime.

  • 4
    $\begingroup$ you might also add that our galaxy moves at close the speed of light from a galaxy at the edge of the observable universe. To answer your question you need to first fix a reference frame, that is, decide what observer is at rest. $\endgroup$
    – user16007
    Commented Aug 30, 2014 at 20:58
  • $\begingroup$ BTW, the Sun oscillates up and down in the galactic plane, so that has to be taken into consideration, too. $\endgroup$
    – HDE 226868
    Commented Aug 30, 2014 at 21:27
  • 1
    $\begingroup$ You might look at what-if.xkcd.com/86 where he compares the distance traveled by Voyager 2 (launched in 1977) to the distance traveled by a 1977 Plymouth Voyager and some other objects in various coordinate systems. $\endgroup$ Commented Aug 30, 2014 at 21:30
  • 1
    $\begingroup$ Have you tried doing the math? It doesn't seem much past dimensional analysis. $\endgroup$
    – Kyle Kanos
    Commented Aug 31, 2014 at 1:12
  • $\begingroup$ I would say you could neglect all other contributions compared to the quickest one. $\endgroup$
    – Bernhard
    Commented Aug 31, 2014 at 8:13

1 Answer 1


In this context, the least ambiguous reference frame is the comoving rest frame. In essence, this is the local frame moving along with the local Hubble expansion. We can accurately determine earth's velocity with respect to this comoving frame (and thereby obtain our so-called peculiar velolocity) by subtracting out the dipole anisotropy from the Doppler shift of the microwave background radiation (the afterglow of the Big Bang). It follows that earth moves at a speed of 371 km/s in the direction of constellation Leo.

Now you can do the math using 371 km/s and the fact that there are 3600 x 24 seconds in a day and 365.25 days in a year.

  • $\begingroup$ Thank you very much, this is exactly what I was looking for. It turns out one travels around 10% of light-year in a lifetime. $\endgroup$ Commented Aug 31, 2014 at 10:10

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