Dark matter

This is a very unusual type of matter thought to exist in huge quantities throughout the Universe. Astrophysicists believe that about 4% of the Universe is composed of matter as we know it, a further 22% in dark matter and the other 74% is something even stranger called dark energy.

It is difficult to explain this simply but dark matter is matter that does not reflect light and gives out virtually no light itself. It has only been suggested to explain the effects that it seems to have on stars within galaxies and on galaxies themselves.

The unexplained gravitational effects between galaxies and between clusters of galaxies have been linked to the existence of dark matter. The galaxies seem to be moving as though there was some massive invisible body producing a huge gravitational force and pulling them from their expected paths.

What actually is dark matter? Well that is even stranger. It is probably made up of two parts.The first, baryonic, is composed of atoms as we know them but grouped into non- luminous bodies like planets. The rest is exotic dark matter made of two sorts of particle – neutrinos (hot dark matter) and weakly interacting massive particles (WIMPS) (cold dark matter).

The photo shows gravitational lensing – an effect that may be due to the presence of dark matter.

Gravitational lensing