Gas clouds raining star stuff onto Milky Way galaxy

This composite radio light image and rendition of our galaxy as seen in visible light shows enigmatic "high-velocity clouds" of gas high above the plane of the Milky Way which rain gas into the galaxy, seeding it with the stuff of stars.

The cloud outlined, and possibly others too, is now known to have low heavy element content and to be raining down onto the Milky Way disk, seeding it with material for star birth. Identifying this infalling gas helps in solving a long-standing mystery of galactic evolution by revealing a source of the low-metallicity gas required to explain the observed chemical composition of stars near the Sun.