Planets & Solar System
The birth of the planets Our Solar System was cooked up in a swirling cloud of gas and dust
8Planetary migrations
During planetary migration, giant planets of the outer Solar System change configurations and locations, moving through smaller bodies. Their havoc gives rise to the asteroid belt, Kuiper belt and Oort cloud
9The Solar System today
The planets' near-circular orbits are a result of the merging of many objects in a disc around the Sun – many other solar systems have planets in wilder orbits
1 Shapeless cloud
4.5 billion years ago, the Solar System's raw materials lay in a cloud of gas and dust. Dominant components were hydrogen and helium, but also carbon, oxygen, nitrogen and dust grains
2 Collapse begins
The trigger for an emission nebula produces condensation in regions of the cloud with high densities. Each gives rise to a group of stars – once the first begin to shine, their radiation helps energise the nebula, dictating where the younger generations of stars form
14
3 Individual systems
As material falls inward, collisions between gas clouds and particles cancel out movements in opposing directions, while the conservation of angular momentum causes the cloud’s central regions to spin faster
