In addition, dark matter can be detected through its gravitational influence on other objects, or even on light itself. It can affect the motion of stars and galaxies. Many galaxies have been found to be rotating much faster that they should. According to Einstein's theory of gravity, they should fly apart. But something unseen seems to be holding them together.
Dark matter can also affect the path of light.
In a phenomenon known as gravitational lensing, dense objects can cause the light of distant objects to bend around it. This can result in distorted images and duplicate images of stars and galaxies. We can tell that something is bending the light, but we can't tell what it is. They include objects such as planets, moons, brown dwarfs, dust clouds, white dwarfs, neutron stars, and black holes. They are too small to glow brightly, but they can be detected through their gravitational effect on light.