How many planets are in the solar system?

There are eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, in order from the Sun outward. Pluto was reclassified as a dwarf planet in 2006.

How much bigger is the Sun than Earth?

The Sun is about 109 times wider than Earth, so roughly a million Earths could fit inside it. It also holds more than 99% of all the mass in the solar system.

Why are the planets so far apart?

The spaces between planets are gigantic and mostly empty — pictures squeeze them together to fit on a page. In reality the gaps grow larger the farther out you go, which is why the outer planets take much longer to orbit the Sun.

What is the difference between the inner and outer planets?

The four inner planets (Mercury, Venus, Earth, Mars) are small and rocky with solid surfaces. The four outer planets (Jupiter, Saturn, Uranus, Neptune) are much larger gas giants made mostly of gas and ice.

How Big Is the Solar System?

Science Interactive lesson Free to play

The solar system is the Sun together with everything that orbits it — eight planets, their moons, dwarf planets like Pluto, plus asteroids and comets. It is vast almost beyond imagining: the Sun alone is about 109 Earths wide and holds more than 99% of all the mass in the solar system, which is why everything else circles around it.

The biggest surprise is the empty space. The four inner planets — Mercury, Venus, Earth and Mars — are small and rocky, while the four outer ones — Jupiter, Saturn, Uranus and Neptune — are giant balls of gas. Between them lie enormous gaps, mostly nothing at all. Distances are so great that scientists measure them in how long light takes to travel: sunlight takes about 8 minutes to reach Earth.

Understanding the solar system's size helps children grasp scale, distance and order in space, and explains why even the fastest thing in the universe — light — feels slow when crossing it.

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A giant question

Space adventure 🚀 How Big Is the Solar System? Our home in space is bigger than almost anything you can imagine. Let's shrink it down so it fits in your head! ☀️ Tap Next to begin your journey from the Sun outward.
The Sun is enormous

Start with the Sun ☀️ The Sun is a giant ball of glowing gas at the centre. Everything in the solar system goes around it. How many Earths do you think would fit across the middle of the Sun? Take a guess, then reveal it! 🌍 ➡️ ☀️ Tap here to reveal the answer… About 109 Earths! You could line up 109 Earths side by side across the Sun. The Sun is the giant of our solar system. No wrong guesses here — guessing first helps your brain learn. 🧠
Meet the planets

The 8 planets 🪐 Eight planets travel around the Sun. Tap each planet to learn its name. The first four are small and rocky; the last four are big gas giants. 👆 Tap a planet Tip: from the Sun outward it's Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
The gaps are huge

Mind the gap! 🛰️ The planets aren't squished together like in the picture. The spaces between them are gigantic — mostly empty. Imagine we shrink the Sun to the size of a basketball 🏀 and put it at your school gate. Where would tiny Earth be? In the same classroom Just across the field About 25 metres away — and the size of a peppercorn! Space is mostly… space! The solar system is huge and very empty.
Even light takes time

So far that even light is slow 💡 Light is the fastest thing there is. It could zoom around the Earth more than 7 times in one second! Yet the Sun is so far away that its light still takes a while to reach us. How long does sunlight take to travel from the Sun to Earth? Less than 1 second About 8 minutes About 8 hours That means you always see the Sun as it looked 8 minutes ago! 😮
Build the solar system

Build it from the Sun out ☀️➡️ Tap the planets in the right order, starting closest to the Sun. If you pick the wrong one, I'll give you a hint! ☀️ Sun → your planets appear here Start this game again
You did it!

Mission complete 🎉 You explored the whole solar system! ⭐ The Sun is a giant — about 109 Earths wide. ⭐ 8 planets orbit it: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. ⭐ The gaps between planets are enormous and mostly empty. ⭐ The solar system is so big that even light takes 8 minutes just to reach Earth. The solar system is one of the biggest things you'll ever learn about — and now you've got it in your head. 🚀🌟 Well done, space explorer!

Frequently asked questions

How big is the solar system?: It is so large that distances are measured by how far light travels. Sunlight takes about 8 minutes to reach Earth and over 4 hours to reach Neptune, the farthest planet, even though light could circle Earth more than 7 times in a single second.
How many planets are in the solar system?: There are eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, in order from the Sun outward. Pluto was reclassified as a dwarf planet in 2006.
How much bigger is the Sun than Earth?: The Sun is about 109 times wider than Earth, so roughly a million Earths could fit inside it. It also holds more than 99% of all the mass in the solar system.
Why are the planets so far apart?: The spaces between planets are gigantic and mostly empty — pictures squeeze them together to fit on a page. In reality the gaps grow larger the farther out you go, which is why the outer planets take much longer to orbit the Sun.
What is the difference between the inner and outer planets?: The four inner planets (Mercury, Venus, Earth, Mars) are small and rocky with solid surfaces. The four outer planets (Jupiter, Saturn, Uranus, Neptune) are much larger gas giants made mostly of gas and ice.

How Big Is the Solar System?

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Frequently asked questions

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