What is dark matter and has evidence of it been discovered yet?

Answer 1

The nature of dark matter is still unknown.

A recent study of a pair of colliding galaxies claims to have found solid evidence of dark matter. Gravitational lensing shows mass concentrations beyond the visible concentrations of gas. The astronomers think this is due to the galaxies' dark matter, which is moving faster than the gas. The gas clouds have been slowed by the collision more than the dark matter, because the gas is susceptible to drag but the dark matter interacts only through gravity.

Answer 2

Back in the past, astronomers believed the universe to comprised only of properly developed structures. These included planets, asteriods, stars, nebulas, etc.

However, all these didn't add up to the total mass of the universe.There is still a lot of mass unaccounted for.

In the 80s, using radio telescopes, astronomers detected other material that exist in the universe. These include charged particles, mesons, sub atomic particles, etc. These material also don't emit radiation and are not detected by telescopes.

If these material can exist, astronomers speculate they may cover the entire universe and make up the lost mass.

That's dark matter!

Answer 3

The previous poster is wrong in some details. The dark matter has been detected only from its gravitational effects. But using those effects, it has been possible to map out its distribution. Among the effects known: graviational lensing, dynamics of stars inside galaxies, and dynamics of galaxies inside clusters of galaxies. It is still completely unknown what it is made of except that it is not made of ordinary protons or neutrons (like regular matter is). It is also not made of the mesons discovered in cosmic rays because those decay too quickly to be candidates.