Peering into the Birthplaces of Solar Systems

The circumstellar disks that naturally arise from the star formation process are the sites where planets are made. Many hundreds of these analogs to the disks that spawned our Solar System are accessible to observation in nearby dark clouds. The revolutionary sensitivity of the new Atacama Large Millimeter/submillimeter Array and Expanded Very Large Array provide dramatically improved tools to study these disks at millimeter wavelengths, a regime that probes directly the location and size distribution of solids, as well as the thermal, chemical, and dynamical structure of gas, all of which impact what kind of planetary system, if any, may form (or may be forming now). I will discuss selected early observations of circumstellar disks from these new facilities, together with pathfinder observations, that constrain initial conditions for planet formation and show evidence of key physical processes in action.