The Remarkable Proto-planetary Disks HL Tau: Watching the Formation of Planets

Spatially resolved ALMA studies of protoplanetary disks at millimeter wavelengths are revolutionizing the study of these precursors to solar systems. In this talk I will present results from observations of the protoplanetary disk HL Tau with 3.5 AU resolution. I will also review the diverse range of modeling work that has emerged to explain the remarkable dust ring structure of HL Tau. Finally, I will show tantalizing new observational results that suggest such structures may be ubiquitous.