My Solar Compass

The iPhone tool for capturing real sunrise and sunset alignments, revealing solstices, feast days and the ancient geometry hidden in buildings and landscapes... or in your own backyard. WHAT IS MY SOLAR COMPASS? Point your iPhone along any structure: a cathedral nave, the axis of a stone circle, a garden path. Solar Compass records the precise compass bearing using your iPhone's GPS, compass and camera. Then it calculates exactly when the sun rises or sets along that line throughout the year. Discover whether that medieval church or mountain peak aligns with the winter solstice. Find which saints' days and feast days match your alignment. See whether ancient builders oriented their structures to catch the sunrise on the longest day of the year. Or keep it close to home and find out how your house and garden are oriented. A JOURNEY THROUGH TIME Calculate the sun for any year from 5000 BC to today. Studying a cathedral built in 1200? Set the year to 1200 and see where the sun rose on the solstices when it was new. This matters because the tilt of the Earth's axis changes slowly over the centuries. The winter solstice sunrise in 1200 was at a slightly different bearing than it is today, and by 3000 BC the difference is larger still. Solar Compass uses the IAU 2006 formulas for the Earth's tilt and VSOP87 for the sun, from Stonehenge to colonial-era buildings. Dates are given the way people wrote them at the time: in the Julian calendar before 1582 and in the Gregorian calendar after. Before the Julian calendar, the app counts back in the Gregorian calendar, so ancient dates are easy to compare. HOW IT WORKS Point your iPhone along the alignment and tap to capture the bearing in seconds. While you aim, the live sun path in the camera shows where the sun rises and sets on the solstices and equinoxes. Each line is stored with its GPS position and a photo. Every site opens on one screen: a satellite map with a compass ring, the sun's solstice and equinox lines for the year you choose, and your own lines. Tap a line to see every day the sun rises or sets along it, with the feast day of each date. Pin the date that matters and it stays with the line. The calculations are far more precise than any phone sensor, so the measurement is what counts. Calibrate your compass on the sun right in the app and measure away from cars, fences and other metal. That brings you within one or two degrees. My Solar Compass works without internet or cell reception; only the satellite map needs a connection. FEATURES - Capture alignments anywhere with your iPhone's compass, GPS and camera - Any year from 5000 BC to today, with the Earth's tilt for that year - Automatic solstice and equinox detection - Feast days from Christian, Chinese, Buddhist and ancient traditions - Satellite site map with a compass ring and the sun's lines for any year - Pin the date an alignment is about - Sun calibration for a more accurate compass - Export your sites to Google Earth - Unlimited sites and lines in your own iCloud Drive, synced across your devices, included in the price - 14 featured sites, including Stonehenge, Newgrange, the Great Pyramid of Giza, Angkor Wat, Machu Picchu, Notre-Dame de Paris and Manhattanhenge WHO IS THIS FOR? Anyone who looks at an old building and wonders: "Why does it face that direction?" Heritage enthusiasts and curious travelers. Students and educators in archaeoastronomy or architectural history. Researchers documenting alignments in the field. Garden designers interested in solar orientation. Photographers planning solstice shoots. YOUR DATA, YOUR RESEARCH Your sites and lines are stored in your own iCloud Drive. There is no account to create, and we never see or share your data. With iCloud Drive on, your research is still there if you delete the app and come back. You own your research. START EXPLORING Let the calculations reveal what builders knew centuries ago: certain directions are special.