Speed of Milky Way Through Space?

I read that the Milky Way Galaxy is traveling over 2 million miles per hour through space. How do we know this? what is this speed in reference to as a point of 0 mph? ....Greg
- Greg (age 56)
Vandalia, Ohio

Nice question.    The velocity, i.e. speed and direction, of our earth can be determined by observing a small anisotropy in the cosmic background radiation.   This anisotropy is attributed to a Doppler shift due to the motion of Earth-MilkyWay system moving with respect to "the rest of the universe".  

See for an explanation and a nice picture.

 

LeeH

 

 

 

(published on 07/03/2013)