Tidal Streams and Galactic orbits

There are at least two great streams around the Galaxy. The Magellanic Stream first discovered by Wannier and Wrixon extends over almost 120 degrees across the Southern sky and is mainly hydrogen gas. By contrast the Sagittarius stream goes all around the sky and is mainly detected via stars and globular clusters. In this talk I develop a powerful approximate way of treating central orbits in non-Keplerian potentials and show how it can be used to predict the shapes and velocities of streams of stars released when a small "victim" is tidally torn apart by a larger galaxy.