Dark Matter: Some Interesting Facts
Hercules Cluster (click to zoom)
☻ Dark matter comprises around 84.5% of the total matter in the universe.
☻ It isn’t made up of baryons, unlike normal matter, which is a combination of protons and neutrons. Dark matter doesn’t interact with electromagnetic forces. It doesn’t absorb or emit light, nor does it reflect it like normal matter. The only way it can be detected is through its gravitational pull on visible matter.
☻ Jan Oort, a Dutch astronomer, was the first to detect the presence of dark matter, in 1932. While studying stellar motions in nearby galaxies, Oort found that the matter seen in the galaxies is quite less as compared to the size of the galaxies.
☻ The ‘missing mass’ problem suggested that, the stars, hot gases, and visible matter in the galaxy clusters accounted for hardly 20% of the total matter in the galaxy. The speed at which these galaxies moved was enough to flow them apart. According to Fritz Zwicky
, a Swiss astronomer, these galaxies needed a lot more mass to hold themselves together, considering their speed. This meant that, there was some matter missing to the human eye, that was holding these galaxies together.