Chapter 1 of 12All chapters
Chapter 1 of 12
The scale of things
Why the pictures are always wrong.
Sizes and gaps
If the Sun were a football, Earth would be a peppercorn 26 metres away and Neptune a small pea nearly a kilometre off. Diagrams shrink the gaps because otherwise the planets vanish.
- The Sun holds 99.8 percent of the mass of the solar system.
- Space is mostly empty, which is why spacecraft cross the asteroid belt without trouble.
Units for distance
Within the solar system, distances use the astronomical unit, the Earth to Sun distance. Beyond it, light years and parsecs take over because the numbers get unusable.