@ThatHil
This is a diagram from a science paper that I grabbed quickly.
Usually when discussing things about the size of our solar system, astronomers use units of AU, astronomical units, the average distance between the Earth and the Sun. It's about 150 million kilometers (93 million miles).
Why? It gives you an intuitive-ish size scale. Much easier than talking about millions of km.
@kellylepo
Thank you :) I meant why minus numbers? Not that I'll probably understand any explanation. Anyway am glad to have discovered there IS a bigger unit of measurement than a football pitch or Wales.