Often several times larger than our own Milky Way galaxy, Lyman-alpha blobs are some of the largest known objects in the universe. (See "Giant 'Blob' Is Largest Thing in Universe.")

The blobs are also unusually bright, shining with the same intensity as the brightest known galaxies. Still, the objects tend to exist in very distant reaches of the universe, so their exact power source has been a mystery.

(Related: "Glowing, Green Space Blob Forming New Stars, Hubble Shows.")