Credit: CTIO/P. Palunas

This visible-light image shows a giant galactic blob containing the three merging galaxies NASA's Spitzer Space Telescope discovered within it.

Blobs are intensely glowing clouds of hot hydrogen gas that envelop faraway galaxies. They are about 10 times as large as the galaxies they surround. Visible-light images like the one shown here reveal the vast extent of blobs, but don't provide much information about their host galaxies.

The visible-light image was taken by the Blanco Telescope at the Cerro Tololo Inter-American Observatory, Chile.