SPACE SPUDS

A nebula (a cloud of dust and gas) the size of earth would weigh the same as a small sack of potatoes.

This is because all the dust and gas in a nebula is really light. However, when the dust and gas stretches over many light years, there is enough mass and gravity for the nebula to collapse and form new stars.

Some of the biggest, most impressive nebulae form from exploding supernovae, an event that can lead to the creation of brand-new stars.

Scientists classify nebulae according to their appearance and how they formed. They can be very large — a few hundred light-years across — and fantastically shaped.

The Horsehead nebula in the Orion constellation is a dark equine shape, in which dense dust absorbs light.