Guess the World is a free daily puzzle about the solar system. Each day (midnight UTC) one planet, moon or dwarf planet is the mystery world. You have six tries. After each guess the game compares your world with the answer for what it orbits, diameter, surface gravity, orbit time and distance from its parent.
Green means an exact match, yellow means within a factor of 1.5, and grey means far. The arrows point toward the answer. Copy your colour grid to share it without spoiling the answer, or use Practice mode for extra worlds.
The eight planets, dwarf planets such as Pluto, Ceres and Eris, and 21 moons including the Moon, Titan, Europa and Triton.
How long the moon takes to go around its planet. For planets it is the time to go around the Sun, in Earth days.
Rounded values from NASA planetary fact sheets. Gravity is measured at the surface, or at the cloud tops for gas giants.
Solve each day's world to extend your streak. Your streak is saved in your browser.
One planet, moon or dwarf planet a day. Six tries. Each clue tells you if the mystery world is bigger, heavier, faster or farther away.