... Observing . ... Star Atlas . ... stars . ... Building planets is a slam-bang art . A survey of a nearby stars finds at least a quarter of them have dust disks born in collisions among rocky, asteroid-size bodies. ... Once large rocks form, collisions among them make planets, and once planets form, collisions with leftover rocks make the bright, warm rings of dust detected by Spitzer and other infrared telescopes. ... By observing stars of different ages, we can see snapshots of our own history. ...