See the sun path in your camera view

1Open the camera view

Tap “Camera” in the navigation at the bottom. The browser asks for the camera, an iPhone also for motion and orientation – allow both. The camera only starts when you tap, never by itself, and SunPosition neither stores nor sends any image.

Hold the phone upright in portrait, as if taking a photo. The dashed line is the horizon, 0° altitude. A button at the top right switches to full screen.

2Align by the sun

At first the view is aligned by the phone's magnetic compass (“Aligned by the magnetic compass”). Next to metal, cars or reinforced concrete it is often off by 10–30° – too coarse for the question “behind which tree?”.

So tap “☀ Align by the sun (more accurate)”. A crosshair and a line at the sun's altitude appear. Tilt the phone up or down until it says “Altitude matches”, then pan sideways until the crosshair sits on the sun, and tap “Sun sighted”.

SunPosition knows the sun's direction for your place and time to better than 0.1°. Your sighting therefore gives true north, and the view then runs on the phone's gyroscope – independent of the magnetic field. If the camera's altitude differs from the sun's by more than 6°, the app rejects the sighting: it was not the sun but, say, a reflection.

3Reading the image

Once aligned, three arcs lie in the image: the path of June 21 (yellow), that of December 21 (blue) and the path of the selected day with hour labels. The sun marker shows the sun at the selected time; if it is outside the frame, an arrow at the edge shows which way to pan. N, E, S and W are marked on the horizon.

The slider below the image moves the time, and the sun marker travels along the arc; “Now” jumps back. Set date and location in the top band as usual – December 21, for instance, to check the lowest path.

Wherever a tree, a roof or a hillside rises above an arc, the sun is behind it on that day at that time. If the winter path is clear, the spot gets noon sun all year round.

4Limits and sources of error

No sun, no accurate alignment: at night, under complete cloud and when the sun is lower than 5°, the magnetic compass remains. If the device reports no compass and the sun is too low, the view cannot start.

The gyroscope in a phone drifts slowly. After about ten minutes, or when the arcs visibly miss roof edges and masts you know, tap “Sight again”.

The arcs apply to the spot where you stand. Two metres to the left a nearby tree already looks different – stand where the deckchair, the window or the solar panel will be.