Star Map
Point your phone's camera at the sky — constellations light up right over the image, in real time, based on your location.
Point your phone at the sky
Nothing is sent anywhere — every calculation happens right on your phone.
What an AR Star Map Is
AR (augmented reality) is when computer graphics are laid directly over the camera image in real time, rather than shown separately from the world around you. Our star map works exactly that way: you see the real sky through your phone's camera, and over it, the precise positions of the stars and the constellation lines, tied to wherever the phone is pointing right now. This isn't a static sky chart or a planetarium with an abstract top-down view — constellations are identified live, from your actual date, time, and coordinates.
How It Works Technically
Your phone determines your location and exactly where the camera is pointing — the compass bearing (azimuth) and the tilt (altitude above the horizon). Knowing the exact time and place, the real current position in the sky is calculated for each of the 1,600+ bright stars in the Yale Bright Star Catalog — the same way real astronomy does it, not from a template. What remains is to project the stars that should be within the camera's field of view onto the screen and light them with a golden glow, along with the lines of 87 of the 88 official constellations. All calculations happen right on your phone, with no server involved.
How to Find a Constellation in the Sky With Your Phone
Open "Star Map" outdoors or by a window, allow access to the camera, location, and orientation sensors — then simply point your phone where you want to look. Constellation names appear right above the real stars, and the constellation you're currently looking at is highlighted more brightly than the rest and shown as a separate caption at the bottom of the screen. A clear night and an open sky (away from bright city lights) give the best result — it's easier to compare the overlay with what you see with the naked eye.