Solar System Scale Explorer
Compare planet sizes and distances across the solar system. Switch between distance-to-scale and size-to-scale views, drag a time slider to watch orbits, and click any planet to see its diameter, day length, year length, and moons.
Orbits are spaced by real AU ratios. Planet diameters are uniform so each body stays visible.
Select a planet
Tap a planet in the scene or use the buttons above to see its size, distance, day length, and number of moons.
Why you cannot show both at once
If Earth were the size of a pea, Jupiter would be about a grapefruit and the Sun would be a beach ball. Place that beach ball at home plate of a baseball diamond and Earth would sit roughly 26 metres away. Neptune would be more than 770 metres past the outfield, still about the size of a small cherry. Any diagram that shows distances accurately must shrink the planets to invisible dots; any diagram that shows sizes accurately must squash the distances. Use the two toggles to see each version one at a time.
NGSS alignment
This tool supports two middle school Earth and Space Science standards.
- MS-ESS1-2. Develop and use a model to describe the role of gravity in the motions within galaxies and the solar system.
- MS-ESS1-3. Analyze and interpret data to determine scale properties of objects in the solar system.
Astronomical units
One Astronomical Unit (AU) equals the average distance from Earth to the Sun, roughly 149.6 million kilometres. Astronomers use AU because the kilometre numbers in the outer solar system are hard to picture. Saturn at 9.5 AU is nine and a half times farther from the Sun than Earth is. Neptune at 30 AU is thirty times Earth's distance.
How the time slider works
One full sweep of the slider equals one Earth year. Mercury rips around the Sun roughly four times in that span. Mars barely makes it half a lap. Jupiter creeps about thirty degrees. Neptune hardly seems to move at all because a single Neptune year is almost 165 Earth years long. Each planet's angular speed comes from its real orbital period.
Planet quick facts
| Planet | Diameter | Distance from Sun | Day length | Year length |
|---|---|---|---|---|
| Mercury | 4,879 km | 0.39 AU | 1,408 hours | 0.24 Earth years |
| Venus | 12,104 km | 0.72 AU | 5,833 hours | 0.62 Earth years |
| Earth | 12,756 km | 1.00 AU | 24 hours | 1.00 Earth years |
| Mars | 6,792 km | 1.52 AU | 24.7 hours | 1.88 Earth years |
| Jupiter | 142,984 km | 5.20 AU | 9.9 hours | 11.86 Earth years |
| Saturn | 120,536 km | 9.54 AU | 10.7 hours | 29.46 Earth years |
| Uranus | 51,118 km | 19.19 AU | 17.2 hours | 84.01 Earth years |
| Neptune | 49,528 km | 30.07 AU | 16.1 hours | 164.79 Earth years |
Sources. NASA planetary fact sheets. 1 AU equals roughly 149.6 million km.
Try these classroom prompts
Predict, then check
Predict which planet is widest before opening Size to scale. Was it the one you expected? How many Earths would line up across Jupiter at its widest point?
Count laps
Press Play and count how many laps Mercury makes for each lap that Earth makes. Does the ratio match the year lengths in the data table?
Spot the belts
Find the asteroid belt between Mars and Jupiter, then the Kuiper belt past Neptune. Toggle the Oort cloud overlay and zoom out. Why does the Oort cloud feel so far away?
Build a hallway model
If your classroom assigns Earth as 1 cm in diameter, how many metres of hallway do you need for Neptune's orbit? Use the data table to compute the answer.
