Dark matter has been mysterious ever since its discovery.
According to Dr Holger Israel, a cosmologist at Durham University in England, "we know that something is there that can't be any of the particles we know about. But we don't have a good idea yet what it is."
Yet that something makes up 85% of the mass in the known universe.
The mystery arises, at least in part, because dark matter is extremely elusive.
It's invisible because it does not interact with light (hence its sinister-sounding name), and it hardly interacts with anything at all, including itself.
It only attracts objects through gravity. However, its effects are huge.
Dark matter coagulates inside and around galaxies, where "its sheer mass...