Unexpected orbital velocities of stars around the centers of galaxies led astronomers to predict the existence of dark _____.
energy
forces
matter
space
galaxies
Unexpected orbital velocities of stars around the centers of galaxies led astronomers to predict the existence of dark matter. Dark matters are hypothetical substance that are believed to account for around five-sixths of the matter in the universe.
The stars are orbiting around a matter which is not visible. This matter is called dark matter. They are very massive thus, their force of attraction is very large.
