This artist’s impression depicts a protoplanetary disk surrounding a star. Material from the disk flows along the star’s magnetic field lines to strike the star’s surface. The ensuing flares can be observed both directly and as echoes once the light reaches and illuminates the inner disk. Timing the echoes yields the radius of the inner disk. Turn to the article by Sean Andrews on page 36 to learn how new observations are enriching our understanding of the disks of gas, dust, and ice that nurture planets. (Image courtesy of NASA/JPL-Caltech.)