Solar System mix
Planets, the Moon, Pluto and the Sun, with reachable size comparisons.
ONE TOPIC. A NEW PERSPECTIVE.
Size It Up Universe
Compare body diameters across the Solar System. Jupiter uses the 2026 Juno equatorial measurement; rings and the solar corona are excluded.
Five comparisons · 500 points
Planets, the Moon, Pluto and the Sun, with reachable size comparisons.
Finding a little perspective…
No timer No sign-up Free to play
Planet size comparisons on one scale
Size It Up Universe asks you to estimate body diameter: the width through the center of a planet, moon or star. The topic includes eight planets, the Moon, Pluto and the Sun. It compares their sizes, not their orbital distances, mass or volume.
Which part of the object counts?
Saturn’s rings and the Sun’s corona are excluded. Use the marked body diameter, not every feature you associate with a picture of the object. Earth can be a useful reference because you may already have a rough idea of its place among the planets.
Why do the measurement notes matter?
Equatorial and mean diameters are different measurements. This topic uses the 2026 Juno equatorial measurement for Jupiter; each reveal identifies the convention and source for that object. The labeled values determine your score, so check them before transferring a comparison from another diagram.
Choose your part of the Solar System
Rocky worlds keeps you among solid-surface bodies. Giants & the Sun explores a different range of sizes, while Solar System mix draws from both groups. Each game selects five comparisons within the slider’s available range.
Rocky worlds
Mercury, Venus, Earth, Mars, the Moon and Pluto.
Giants & the Sun
Jupiter, Saturn, Uranus, Neptune and the Sun.
Keep exploring
See the Jupiter and Earth size comparison to separate width, volume and mass, then explore the Sun and Jupiter size comparison. To replay the same five pairs, choose the rocky planet and moon collection.