What did we learn about the Milky Way during the last decade, and what
shall we learn using Gaia and LSST?

Zeljko Ivezic, University of Washington

Studies of stellar populations, understood to mean collections of
stars with common spatial, kinematic, chemical, and/or age
distributions, have been reinvigorated during the last decade by the
advent of large-area sky surveys such as SDSS, 2MASS, RAVE, and
others. These data, together with theoretical and modeling advances,
are revolutionizing our understanding of the nature of the Milky Way,
and galaxy formation and evolution in general. These recent
developments have made it clear that the Milky Way is a complex and
dynamic structure, one that is still being shaped by the merging of
neighboring smaller galaxies. I will review the progress over the last
decade, including the mapping of stellar counts, metallicity and
kinematics distributions, interstellar dust using extinction of stars,
and dark matter halo using Jeans equations. I will conclude by briefly
discussing new breakthroughs expected from Gaia and LSST surveys,
which will improve measurement precision manyfold, and comprise
billions of individual stars.