We might be stardust, Joni Mitchell sang of Woodstock in 1969, echoing what was already a half-century of hard-headed astronomical truth. But astronomers have struggled to understand just exactly how stardust goes from being cosmic smog, littering the lanes of the galaxy, to planets and people.

Recently, however, astronomers using the Atacama Large Millimeter/submillimeter Array, or ALMA, an international radio telescope in the high desert of Chile, obtained what might be the best picture yet of dust in the act of turning into planets.

It shows a young star named HL Tauri, about 450 light-years from here and thus in the constellation of Taurus. The star is surrounded by a glowing disk of dust and gas about 22 billion miles across — about four times the size of Neptune’s orbit, which bounds the realm of official planets in our own solar system ever since the outlier Pluto was bounced from the fraternity of planets.

Most significant, the disk is scored with dark rings or grooves, like a record or the rings of Saturn.