How to stargaze with your phone (AR), step by step — and fix a drifting compass
The AR mode in Spider Astro uses your phone's rear camera as the background and overlays the positions of stars, planets and constellations on the real sky. It is free and needs no app install.
Step by step
- Open the site in Chrome or Safari. If you tap a link inside LINE or Facebook, the in-app browser often blocks the motion sensors — choose “Open in browser”.
- Tap “Stars in AR via camera” on the home screen (the teal button).
- When asked, allow the camera and allow motion and orientation sensors (iPhone asks separately).
- Raise your phone toward the sky; the star labels move as you turn around.
- Tap “☰ Menu” at the bottom centre for options: search for a particular star and follow the pink arrow, switch names and constellation lines on or off, take a photo.
- Tap the ✕ at the top right to leave the mode and return to the home screen.
If the labels are off, calibrate the compass
- Move your phone in a figure-8 in the air a few times so the sensors recalibrate.
- Stay away from metal and magnets, including magnetic phone cases.
- Aim at the Moon or a bright star you can really see and compare it with its label; if it is still off, drag left or right on the screen to line it up.
Common problems
| Problem | Fix |
|---|---|
| Camera does not start | Check that camera access is allowed for the site and that the address starts with https. |
| Labels do not follow the phone | Sensor permission was not granted. Open the site in Safari/Chrome and try again, or drag on the screen to rotate the sky. |
| No stars in daytime | Most stars cannot be seen by eye in daylight, but you can still compare the Sun's and Moon's positions. |
| Labels do not match the real sky | Calibrate the compass as above. |
Privacy
The camera image is shown on your device only; the site does not save or upload it. If you take a photo and other people appear in it, especially their faces, ask permission before sharing, and take extra care with photos of children.
Limits
Accuracy depends on your phone's sensors. Star positions are calculated for your time and place, but the overlay can be slightly off. If the sky is overcast the app shows where the stars should be; it cannot see through clouds.
📷 Open the app and tap “Stars in AR via camera”