A team of astronomers that were led by Yale University's Professor Pieter van Dokkum, have discovered a galaxy comprised of almost all dark matter. The galaxy, named Dragonfly 44, was originally overlooked because of its size being as large as the Milky Way. The Dragonfly 44 was also very dim and had few stars.

Pieter van Dokkum said that after its discovery, they had realized that the galaxy had to have more than what meets the eye. So, with the use of some of the world's most powerful telescopes, the astronomers had discovered that the stars moved at velocities that were greater than expected for a dim galaxy.

Co-author of the research paper, Roberto Abraham of the University of Toronto, says that the velocities of the stars meant that the Dragonfly 44 has a huge amount of unseen mass.

The scientists have estimated that the galaxy has a mass that is similar to the Milky Way's at 1 trillion times the mass of the Sun. But only 1 percent of the mass is made up of stars and "normal" matter.

It is still not known as to what dark matter is but it is hypothesized to make op 85-90 percent of the universe.

There have been other galaxies that have been made of dark matter but this galaxy is about 10,000 times more massive.