High above us in space, the Earth, Sun and Moon are always moving in a steady, gentle dance. Understanding it explains why we have day and night, and why a year is a year.
The Sun is a star
The Sun is a huge, hot ball of glowing gas — a star, just like the stars at night, only bigger and brighter because it is closer. The Sun sits at the centre, and the Earth travels round it.
Day and night — the Earth spins
The Earth is always spinning around an imaginary line called its axis, turning once every 24 hours — one day. The side facing the Sun has daytime; the side turned away has night.
A year — the Earth orbits the Sun
As well as spinning, the Earth travels in a big circle around the Sun — this journey is an orbit, and one full orbit takes about 365 days, one year.
| Movement | What it makes | How long |
|---|---|---|
| Earth spins on its axis | Day and night | 24 hours (1 day) |
| Earth orbits the Sun | One year | about 365 days |
| Moon orbits the Earth | A month (roughly) | about 28 days |
The Moon orbits the Earth
The Moon circles the Earth, taking about 28 days. It does not make its own light — we see it because sunlight bounces off it. As it moves, we see different amounts of its lit side, called phases, from a thin crescent to a full round Moon.
All roughly ball-shaped
The Earth, Sun and Moon are all approximately spherical — shaped roughly like a ball, not flat, as photographs from space show.
Many people of faith have long looked up at the steady order of day following night, and the changing Moon, and reflected on them as signs to be grateful for in nature. That reflection does not change the science: the Earth spins, the Earth orbits the Sun, and the Moon orbits the Earth.