Comparing the sizes and order of the planets
Physics · Key Stage 2 · The School
Eight planets, in order
From the Sun outward: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. The first four — Mercury, Venus, Earth, Mars — are small and rocky. The next four — Jupiter, Saturn, Uranus, Neptune — are enormous and made mostly of gas. That split, rocky then gas, is not a coincidence of naming; it reflects how the solar system actually formed.
Sizes are wildly different
Jupiter is so large that over a thousand Earths could fit inside it. Mercury, the smallest planet, is barely bigger than our own Moon. A model of the solar system drawn to scale needs its planets scattered across a very large area, or the biggest ones would swallow the smallest completely.
Why the outer four are called gas giants
Jupiter, Saturn, Uranus and Neptune have no solid surface you could stand on — they are enormous balls of gas, sometimes with a small rocky or icy core buried deep inside. That is why they are called GAS GIANTS, and why no spacecraft has ever landed on one the way rovers have landed on Mars.
A model of the solar system is laid out along a football pitch, with the Sun at one goal. On this scale, Mercury, Venus, Earth and Mars are all tiny dots clustered close to the Sun's end. Jupiter, much further along, is drawn as a large marble. Neptune sits almost at the far goal line, a tiny dot again, but now a very long way from the Sun. The huge empty gaps between the dots are not mistakes — they are the actual scale of the solar system, made visible.