Solar System to Scale
Textbook pictures squash the planets together. Scroll from the Sun to Neptune at true scale, ride a light beam, and see how small Earth really is next to Jupiter and the Sun.
Class 6 Ch 12 Beyond Earth← Scroll or swipe sideways to travel. Distances are to scale; planets are drawn bigger so you can see them.
- 🚶 Walking–
- 🚗 Car–
- ✈️ Plane–
- 🛰️ Fastest spacecraft–
- 💡 Light–
Try this
0 of 5 doneFly out to Mars.Hint: scroll the strip sideways, past Earth
Make it all the way to Neptune.Hint: it's a long way. Keep scrolling, or ride a light beam
Ride a light beam from the Sun to Jupiter.Hint: press “Ride a light beam”
Find the biggest planet.Hint: switch to Sizes and tap the planets
Find out how many Earths fit across the Sun.Hint: in Sizes, tap the Sun
What's happening
Space is mostly empty
Pictures of the Solar System squeeze the planets close together so they fit on a page. In reality the gaps are enormous. If the Sun were a football, Earth would be a peppercorn about 24 metres away, and Neptune would be over 700 metres away.
Even light takes time
Light is the fastest thing there is, about 3 lakh kilometres every second. Still, sunlight takes 8 minutes to reach Earth and over 4 hours to reach Neptune. When you look at the Sun, you see it as it was 8 minutes ago.
Giants and pebbles
The four inner planets (Mercury, Venus, Earth, Mars) are small and rocky. The four outer planets are giants made mostly of gas and ice. About 11 Earths fit across Jupiter, and about 109 fit across the Sun.
Who figured this out?
Aristarchus of Samos
About 270 BCE, GreeceUsed the angle between the Sun and the half Moon to argue that the Sun is far bigger than Earth, and suggested that Earth goes round the Sun.
Johannes Kepler
1619, GermanyFound the rule linking each planet's year to its distance from the Sun, so all the planets' relative distances could be worked out.
Ole Rømer
1676, DenmarkTimed Jupiter's moons and noticed they ran 'late' when Jupiter was farther away. He realised light takes time to travel: the first measurement of the speed of light.
Learn more
- Solar System · NASA Science
- Astronomical unit · Wikipedia
Check yourself
1. About how long does sunlight take to reach Earth?
2. Which is the largest planet?
3. Which planets are the rocky inner planets?
4. If you could drive a car at 100 km/h to the Sun without stopping, it would take about…
Common questions
What is the distance of each planet from the Sun?
Average distances: Mercury 58 million km, Venus 108 million km, Earth 150 million km (1 AU), Mars 228 million km, Jupiter 778 million km, Saturn 1.43 billion km, Uranus 2.87 billion km and Neptune 4.5 billion km.
What is an astronomical unit (AU)?
An astronomical unit is the average distance between Earth and the Sun, about 149.6 million kilometres. Astronomers use it to measure distances in the Solar System: Jupiter is about 5.2 AU from the Sun and Neptune about 30 AU.
How long does light take to reach Earth from the Sun?
About 8 minutes and 20 seconds. Light travels about 3 lakh kilometres per second and the Sun is about 150 million km away. Sunlight takes about 4 hours 10 minutes to reach Neptune.
What are the sizes of the planets compared to Earth?
Compared to Earth's diameter: Mercury 0.38, Venus 0.95, Mars 0.53, Jupiter 11.0, Saturn 9.1, Uranus 4.0 and Neptune 3.9. The Sun is about 109 times wider than Earth.
Why don't textbook pictures show the Solar System to scale?
Because the planets are tiny compared with the distances between them. If you drew Earth as a 1 mm dot, Neptune would have to be about 350 metres away from the Sun, far beyond the edge of the page.
What are inner and outer planets?
The inner planets, Mercury, Venus, Earth and Mars, are small and rocky and lie inside the asteroid belt. The outer planets, Jupiter, Saturn, Uranus and Neptune, are much bigger and made mostly of gas and ice.
Average distances from the Sun; real orbits are slightly oval, so distances change a little through each planet's year.
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