Galaxy formation: the new Milky Way

Nature News feature story on our current understanding of the evolution of the Milky Way. Contains a fine example of the amazing precision achieved by modern science:

"In May, Roeland van der Marel at the Space Telescope Science Institute and his colleagues compared Andromeda’s position over time with background galaxies, and measured its proper motion to an accuracy of 11 microarcseconds per year — roughly equivalent to watching human fingernails grow from the distance of the Moon."