Earth, Moon, Sun System

3.1 - Be able to use the relative sizes of the Earth, Moon and Sun

3.2 - Be able to use the relative distances between the Earth, Moon and Sun

3.4 - Be able to use information about the mean diameter of the Sun (1.4 × 106 km)

The Sun is approximately 400 times further away from us than the Moon.

The Moon is 400 times smaller than the Sun.

Because of this, the Sun and Moon appear to look the same size in the Sky.

We can see eclipses of both bodies from Earth. The Sun and Moon are responsible for tides on Earth. Understanding how big and how far away each is from us has been measured over thousands of years.


Estimate with your fingers how large you think the Moon to be at arm’s length. Next time you see the Moon, try this again. Most people are surprised to find that their little finger will obscure it.

Earth, Moon, Sun Size and Distance
  Approx. Size (km) Average Distance (km)
Sun 1,400,000 150,000,000
Moon 3,500 385,000
Sun divide Moon 400 390