Epicycle: Learn the Sky

Look up. Ask questions. Discover together. Epicycle is a free astronomy companion from FlowDevs for curious explorers and families. Learn about the sky at home, in a classroom, or outdoors—without accounts, ads, subscriptions, or in-app purchases. LEARN ANYWHERE Explore educational cards for the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. Discover all 88 constellations, their guide figures, stories, and modern astronomy facts. Search the bundled star catalog and learn what brightness, coordinates, and spectral types mean. TRY A SPACE QUIZ Answer five questions at your own pace. Every answer comes with an explanation, and you can play again whenever you like. EXPLORE A SKY MAP Choose one of six example cities and change the viewing time. Watch how the modeled sky changes, show or hide constellation lines, and tap solar-system objects to learn more. No camera or location permission is needed. MEET THE LIVE SKY On supported iPhones and iPads, use the rear camera, location, and motion sensors to view an approximate sky overlay. Tap a planet or constellation for its educational card. Adjust heading alignment when nearby magnets or compass interference cause an offset. PRIVATE BY DESIGN All astronomy calculations and learning content run on your device. Camera images, location, and motion data are not uploaded or shared by Epicycle. Learn, Explore, the quiz, and the sky map work offline without camera or location permission. Explore outside with a grown-up and stay aware of your surroundings. Never look directly at the Sun or point binoculars or a telescope at it. Sky positions are educational estimates; visibility depends on daylight, weather, buildings, and light pollution. Camera alignment depends on the device’s sensors. Made by FlowDevs. A window to the cosmos, free for everyone.