On Earth, we are familiar with bubbles associated with soap or carbonated water. These bubbles consist of a thin film of liquid enclosing a volume of air or other gas that is only a few inches across.

In 1790, William Herschel discovered NGC 3079, a nearly edge-on barred spiral galaxy in Ursa Major about 50 million light-years away. Hubble images reveal its spiral disk is peppered with many HII ...