Dark Matter

♤ In astronomy and cosmology, dark matter is a type of matter hypothesized to account for a large part of the total mass in the universe.

♤ Dark matter cannot be seen directly with telescopes; evidently it neither emits nor absorbs light or other electromagnetic radiation at any significant level.

♤ Its existence and properties are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe.

♤ Dark matter is estimated to constitute 84% of the matter in the universe and 23% of the total energy density (with almost all the rest being dark energy).

♤ It is called dark matter because it does not interact with light. Dark matter interacts with ordinary matter through gravity and binds galaxies together like an invisible glue.

♤ While dark matter pulls matter together, dark energy pushes the universe apart at ever-increasing speeds. In terms of the total mass-energy content of the universe, dark energy dominates. Even less is known about dark energy than dark matter.