Dark Matter

Dark matter is invisible matter that does not give off light but reveals itself through gravity, helping hold galaxies and galaxy clusters together.

Imagine seeing leaves swirl around an invisible person: you cannot see the person, but the movement reveals that something is there. Scientists cannot see dark matter directly, but they detect its gravity through the motion of stars and galaxies.

Dark matter is the name scientists give to unseen matter whose gravity affects visible objects. Galaxies rotate and galaxy clusters bend light in ways that cannot be explained by the matter we can see alone. Dark matter does not emit, absorb, or reflect enough light for telescopes to detect it directly, and scientists still do not know what particles it is made of. Its gravity helps gather matter and build galaxies and large cosmic structures. Dark energy is entirely different: dark matter pulls through gravity and helps hold structures together, while dark energy is the name given to whatever is causing the expansion of the universe to accelerate.