NASA is asking the public to help study dust inside distant galaxies. Sometimes two galaxies line up when seen from Earth and appear to overlap. The farther galaxy then works like a flashlight, shining through the nearer one. Its light makes the dust stand out as dark shapes. By studying these shapes, astronomers can map where the dust is and how it dims starlight.
First, however, scientists need to find these rare pairs. A new online project called Overlap Zoo invites volunteers to help. Volunteers look at images that may show overlapping galaxies. They confirm the pairs, describe each galaxy's main features, and mark their outlines. No experience is needed, and the project teaches people as they go. The results will help build the first big list of galaxy pairs that can be used to study dust. They could also improve estimates of distances to faraway objects.