What Are Comets?

How comets change as they journey around the Sun, what are they made of and where are they found? Physics - Universe - Learning Points. Comets formed from dust and ice particles when the Solar System was very young. There are at least a hundred million comets orbiting our Sun. The centre of a comet is called its nucleus. The cloud surrounding a comet's nucleus is called the coma. A Twig Context Film. Reinforce and extend the learning required by the curriculum. Twig’s context films show abstract concepts in action in the real world.