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. FIND A LITTLE WONDER TONIGHT Choose from more than 34,000 offline cities, enter coordinates, or optionally use your location. Tonight suggests bright stars, the Moon, and planets with approximate viewing windows. Follow a guided first discovery onto the sky map, with directions and a simple tip to help you look. REMEMBER YOUR DISCOVERIES Save favorite observing places and keep your chosen city or custom location between visits. When you see an object, record it in My discoveries with the time and place of your first observation. Revisit its educational card or find it again on the map. Your collection stays on your device. 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 Play ten-question rounds at Explorer or Astronomer level. Discover picture questions and questions about today's sky. Every answer comes with an explanation, and you can explore the matching learning cards. EXPLORE A SKY MAP Choose a place and change the viewing time. Watch how the modeled sky changes, show or hide constellation lines, and tap stars, constellations, and 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. Saved places and discoveries are stored locally. Camera images, location, and motion data are not uploaded or shared by Epicycle. Learning, Tonight, 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 and viewing windows 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.