Planetary Systems

The past decade brought direct evidence of the previously surmised exoplanetary systems. A variety of planetary system types exist: those around pulsars, around both young and old main-sequence stars (as evidenced by planetesimal disks of the Beta Pictoris-type), and the mature giant exoplanets found in radial velocity surveys. The surprising diversity of the exoplanetary systems is addressed by several theories of their origin. This revised version was published online in July 2006 with corrections to the Cover Date.