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About
Space
Planetarium
How far is the horizon
How big are galaxies
What happens when you zoom out
When a picture squashes the numbers
Measuring the sky with your hand
Why a day is longer than one spin — on most planets
Does the Moon go round the Earth?
Why the sea goes up and down
A catalogue of everything
Stars that change brightness
How a star is born, and the ways it can end
How the universe began · and how anyone could know
Where a space telescope parks · the Lagrange points
Where does the solar system end?
The whole argument, in one page
1 · The size of the Earth
2 · The size and distance of the Moon
3 · How the solar system is arranged
4 · The distance to the Sun and planets
5 · The distance to nearby stars
6 · The distance to other galaxies
7 · The scale of the universe
What is left to explain
What this site does not cover