The Sky at Night reports on one of the most unnerving discoveries in space science - that most of the universe is missing.<br /><br />We live in a material world, so instinctively we know what normal matter is - the world around us, the planets, stars and interstellar dust. But scientists currently estimate that 95 per cent of everything in the universe is actually - one way or another - invisible. Some of this is ordinary matter that we just can't easily see. But there's also stuff that's much more weird. For instance, there's a new kind of matter we think is out there, but whose very existence is still largely hypothetical - dark matter.<br /><br />And most mysteriously of all, scientists think there is an unknown form of energy pervading the universe that we know so little about, all it has so far is a name - dark energy.<br /><br />The Sky at Night takes you on a tour of this invisible universe, and shows how its existence - or lack of it - will define the fate of the entire universe.<br />
