About this model
The animation shows the eight planets in order from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Their speeds are to scale: Mercury races round in 88 days while Neptune takes about 165 years, so at most speeds Neptune barely seems to move. The distances and sizes are not to scale. If Earth were a 1 cm marble, the Sun would be about 1 metre wide and 117 metres away, and Neptune would be 3.5 kilometres away, far too big for any screen.
Key ideas for young astronomers
- AU means astronomical unit, the average distance from Earth to the Sun, about 150 million km.
- Rocky planets: Mercury, Venus, Earth and Mars are small and made of rock and metal.
- Gas giants: Jupiter and Saturn are mostly hydrogen and helium.
- Ice giants: Uranus and Neptune contain more water, ammonia and methane ices.
- Gravity: on Mars you would weigh about 38% of your Earth weight; on Jupiter about 2.5 times as much.
What about Pluto?
Pluto was called the ninth planet until 2006, when the International Astronomical Union created the category of dwarf planet. Pluto orbits in the Kuiper Belt with many similar icy worlds and has not cleared its orbit of other objects. Other dwarf planets include Ceres, Eris, Haumea and Makemake.
Moon counts change as astronomers discover new small moons; the numbers here follow NASA’s current counts. Want to see real space objects moving now? Try our ISS tracker and Sun & Moon today.
Frequently asked questions
Why are the planets not to scale?
Real distances are so large that the outer planets would be far off any screen. Orbit speeds are to scale.
Which planet has the most moons?
Saturn, with 146 confirmed moons in NASA’s count, followed by Jupiter with 95.
Is Pluto a planet?
Since 2006 it is classified as a dwarf planet.
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Data and credits: Planet facts: NASA Solar System Exploration (public domain), summarised in our own words. See all Kids learning tools and our credits page.