TIMHi, I'm Tim Peake. I'm an astronaut based here at the European Space Agency in Germany, and from December 2015, to June 2016, I spent six months orbiting Earth on the International Space Station.

Narrator: Serious scientists, like myself, believe our solar system was formed by the collapse ... This theory was known as the heliocentric model. It was controversial as accepted wisdom at ...

The Oort cloud is traditionally thought of as a vast shell of perhaps trillions of icy objects encasing our solar system ... its makeup might be. At a heliocentric distance ranging from 10,000 ...