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The Andromeda Galaxy is approaching the Milky Way at about 110 kilometres per second (68 mi/s). What is the velocity that Milky way is approaching M87 ?

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  • $\begingroup$ 1307 km/sec $\endgroup$ – John Rennie Jun 2 '14 at 19:19
  • $\begingroup$ but moving apart, not approaching. $\endgroup$ – DavePhD Jun 2 '14 at 19:28
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The Milky Way and M87 are moving apart at 1231 km/s.

http://ned.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=M+87&img_stamp=yes&extend=no

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  • $\begingroup$ i read this : "the entire Virgo Cluster recedes from us at an average of about 1000 km/sec. But while all the other galaxies in the Cluster recede from us at somewhere around that speed, Messier 86 approaches us at some speed between 244 and 419 km/sec" Is this correct? M87 is blue-shifted? $\endgroup$ – Mateus Jun 2 '14 at 19:33
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    $\begingroup$ M86 is approaching and blue shifted ned.ipac.caltech.edu/cgi-bin/… M87 is receding and red-shifted $\endgroup$ – DavePhD Jun 2 '14 at 19:36
  • $\begingroup$ by the size of M86 and its gravitational pull, the milky way is traveling at 244 km/s toward M86. But M86 is not going toward Milky way at this speed, right? i think it is going towards mk in just a fraction of this velocity, am i right? $\endgroup$ – Mateus Jun 2 '14 at 19:41
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    $\begingroup$ you would have to pick a frame of reference that you consider static. For example, M86 is moving about 106 km/s relative to the CMB rest frame and the Milky Way is moving about 370 km/s relative to the CMB rest frame mnras.oxfordjournals.org/content/386/4/2221.full $\endgroup$ – DavePhD Jun 2 '14 at 20:09
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    $\begingroup$ It's undefined, because there is nothing to which the ship is stationary. There is no such thing as "absolutely stationary". Motion relative to the Cosmic Microwave Background (CMB) is the closest thing to an absolute frame. See physics.stackexchange.com/questions/25928/… $\endgroup$ – DavePhD Jun 2 '14 at 21:25

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