Subaru Telescope/National Astronomical Observatory of Japan

ScienceShot: A Mysterious Galactic Halo

There's nothing wrong with your computer screen. This view of the spiral galaxy M81 is deliberately off-center. That's because the image, taken with the 8.2-meter Subaru Telescope in Hawaii, is focused on the strange structure surrounding the galaxy. Astronomers say it's like nothing ever observed before. It doesn't resemble the halo surrounding our own Milky Way galaxy or the one around our nearest neighbor, Andromeda. Those halos are made of the stars from smaller galaxies that were consumed by their much-larger neighbors. But M81, located about 11.7 million light-years away in the constellation Ursa Major (also known as the Big Dipper) is showing something quite different: The stars sit amid gigantic wispy clouds, which Subaru's instruments indicate contain elements heavier than star-forming hydrogen and helium. Whether M81's halo comprises the remnants of very strange galaxies, or something other than galaxies, remains to be discovered.