Play a planet and moon size game using NASA/JPL mean-radius data for planets, dwarf planets, and satellites. Play it directly on this page.
Play Planet & Moon Size directly on this page. Each round asks, “Which world has the larger mean radius?” Both mean radius values stay hidden until you choose, then the verified answer, source, and snapshot date appear together. The format turns space and astronomy-trivia knowledge into a quick decision without pretending the catalog is a live ranking service.
Planet & Moon Size compares mean radius in km. The only question used for scoring is “Which world has the larger mean radius?” Names, fame, price, popularity, or visual size do not change the answer unless they are part of that metric.
First comparison: Jupiter appears against Earth, giving the player a broad calibration round before later pairings move into much closer planetary and satellite scales.
Second comparison: the Moon faces Pluto, a comparison that tests remembered labels against measured mean radius rather than assuming every planet-like body must be larger than a moon.
Third comparison: Titan appears against Mercury, showing why large natural satellites belong in the same radius game when the metric and units are consistent.
NASA/JPL planetary and satellite physical-parameter tables normalized to mean radius in kilometers. The catalog records a source URL, verification date, and snapshot date for each item. Reviews run on a yearly cadence, so the figures are intentionally described as a dated comparison snapshot.
Every answer uses mean radius in kilometers. The game does not compare diameter, mass, volume, surface area, orbital distance, gravity, visual brightness, or an image’s apparent size. Rows without a positive JPL mean radius are excluded.
Learn a few anchors: gas giants, ice giants, terrestrial planets, the largest moons, dwarf planets, and small irregular moons. Famous names are not always larger. If two bodies occupy the same band, think about whether one is a major spherical moon or a much smaller irregular satellite before choosing.
Replay Planet & Moon Size, follow a related mode below, or use the games directory to switch metrics. Search variations such as space size higher or lower, which moon is bigger, planet radius comparison game are answered here instead of being split into near-duplicate articles.
It shows two Planet & Moon Size items with both values hidden, asks which has more, and reveals the verified figures and sources after your choice.
No. The mode uses NASA/JPL planetary and satellite physical-parameter tables normalized to mean radius in kilometers and is reviewed on a yearly cadence for comparison play.
Use the related links on this guide or return to the games hub to choose another metric with the same More or Less rule.