DAVIS, Calif., Jan. 19 (UPI) -- U.S. astronomers say a small galaxy 7 billion light-years from Earth, invisible to telescopes, may be completely made of dark matter, which reflects no light.
The distant and extremely small galaxy orbits as a satellite of a larger galaxy, they said.
Though telescopes are unable to observe the dwarf galaxy, scientists detected its presence through the tiny distortions its gravity causes in light passing near it, msnbc.com reported Wednesday.
Scientists think dark matter makes up about 98 percent of all matter in the universe but have been unable to detect it directly.
Dark objects like the tiny, distant galaxy could give clues to what exactly dark matter is and how it affects regular matter around it, they said.
Dwarf galaxies are found throughout the cosmos -- even our own Milky Way has them -- and our own galaxy's Sagittarius dwarf satellite is about the same size as the newly detected dark galaxy.
"For the first time we're getting information about something with a mass that's comparable to some of the smaller Milky Way satellites (like the Fornax and Sagittarius dwarfs) but outside of the local universe," study co-author David Lagattuta of the University of California, Davis, said.
"Add in the fact that it's something like 6 (billion) or 7 billion light-years away, it's really true that we've never been able to see something like this before."
