Astronomers have seen how star formation occurs in the center of our own Milky Way Galaxy by using a telescope based at the South Pole. The observations contribute to our knowledge of how stars form in “bursts” near the center of the galaxy at roughly 500-million-year intervals. The scientists were able to show that a ring of material near the galaxy center contains, on average, several thousand molecular hydrogen molecules per cubic centimeter. This density is near a critical value. If the density is below this value, then the ring can persist as a uniform ring of material in orbit around the galactic center. If additional material is added, however, increasing the density, then the ring will come together under its own gravity and form a giant molecular cloud. Gravitational and hydrodynamic forces will then cause this cloud to spiral into the galactic center, where it will cause an energetic burst of star formation.