Ask A Scientist© Astronomy Archive

Author:      pieter de bruin
How is the size of our galaxy determined?
How is the motion and shape of our galaxy established?  

Response #:  1 of 1
Author:      asmith
I believe the best observations are made with radio waves, because they can
penetrate the gas and dust that obscures the visible light from all the
stars in the galaxy.  In particular, the galaxy has big clouds of hydrogen
whose positions and speeds can be determined from the radio observations,
and this gives a rough map of the galaxy.  But your question is a good one: 
our galaxy is a lot harder to figure out than some of the others which are
much further away, because from where we are we do not have a very good
perspective view of it!