‘Planetary Nebula’ (via HubbleColor)

Spiral Galaxy NGC 3310

No one knows what dark matter is, but it constitutes 80 percent of the matter in our universe. By studying numerous dwarf galaxies — satellite systems that orbit our own Milky Way galaxy — NASA’s Fermi Gamma-ray Space Telescope has produced some of the strongest limits yet on the nature of the hypothetical particles suspected of making up dark matter. Short, narrated video.
credit: Wu, Hahn, Wechsler, Abel(KIPAC), Kaehler (KIPAC)