Drexel University Physics Colloquium - ADDED

ABSTRACT: In the first part of the talk I will describe the Green Bank 100-meter diameter radio telescope, its origin and capabilities, and some of its recent scientific programs including the search for gravitational radiation, Mercury's molten core, interstellar organic chemistry, and the growth and evolution of galaxies. The second part of the talk will expand on the topic of growth and evolution of galaxies, with a focus on the Milky Way's need for continual accretion of fresh material, and the discovery of a large gas cloud in the process of merging with our galaxy. This unique object holds information on the evolution of the Galaxy, the structure of the gaseous halo,and the existence of dark matter halos.