Overview
The outer halo of the Milky Way contains a fossil record of its assembly history, and traces the global gravitational field of our galaxy. Stars in the outer halo are challenging to identify and characterize, but recent advances have enabled spectroscopic observations of luminous giant stars to a hundred kiloparsecs and beyond. I will summarize results from our all-sky spectroscopic survey of the most distant stars in the Galactic outskirts. We unveil enormous stellar structures imprinted by the MW’s last major merger, and discover the long-sought stellar counterpart to the Magellanic Stream. We derive the most comprehensive measurements of the MW’s global dynamical response to the infalling Large Magellanic Cloud, providing an independent constraint on the dark matter distribution in both galaxies. I conclude with an outlook towards what future surveys will teach us about our galaxy and the physical nature of dark matter.