Roughly estimating direction from the sun

The Earth turns from west to east. To us it therefore looks as if the sun moves across the sky from east to west. A stick's shadow moves the opposite way – so its tip travels from west to east. This is true in both the northern and the southern hemisphere.

At midday the sun is at its highest and the shadow at its shortest. Outside the tropics, in the northern hemisphere the sun is then roughly south, and the shadow points roughly north. In the southern hemisphere it is the other way round. But careful: 'midday' here means the sun's highest point, not 12 o'clock on your watch. Time zones and daylight saving can shift that moment by an hour or more.

Sunrise and sunset also give only a very rough indication. Only around the spring and autumn equinoxes does the sun rise almost exactly in the east and set in the west. In the northern summer, sunrise is clearly north of east, in winter clearly south of it – the further from the equator, the more so.

The ground should be as level as possible and the stick upright. A longer stick casts a longer shadow on which the movement is easier to see. Mark the shadow tip as exactly as possible – a small stone or twig right at the tip.

The longer you wait, the clearer the movement and the less small marking errors matter. A quarter of an hour is the minimum; more time usually makes the result more reliable. With clouds that keep hiding the sun it gets difficult, because the shadow blurs.

Check the result against everything else you know: where is the sun right now? Which way does the stream flow according to the map? Where is a summit you recognise? If the clues contradict each other, do not trust the method blindly.

The method helps when you have no compass and only want to know roughly where north is – for example to orient a map roughly, or to check whether a direction is plausible at all. It is too imprecise for accurate navigation.

In the tropics the sun stands very high around midday, almost straight overhead. The shadow is then tiny and its movement hard to see. At high latitudes, far north or south, the sun is often very low and the shadow becomes extremely long. In both cases the method is particularly unreliable. Under complete cloud cover it does not work at all.

Important: when you are lost, the first thing you usually need is not a compass direction but a clear plan. The shadow-stick method replaces neither the STOP rule nor an emergency call.

A direction that is only slightly wrong leads far from the target over a long distance. Just a few degrees off means hundreds of metres of offset after a few kilometres. So the shadow method is better suited to finding a rough direction towards a long line you cannot miss – such as a big road or a river – than to hitting a small target precisely.

Well-known 'rules of thumb' such as 'moss grows on the north side of trees' are unreliable. Where moss grows depends on moisture, shade, wind and the individual tree. Lopsided trees or anthills are not reliable compasses either.

Try the method on a sunny day in the garden or a park where you already know the directions or can check them with a compass. Do it once in the morning, once at midday and once in the afternoon. That way you see for yourself how well or badly the result fits at different times of day.

For children it is an exciting experiment: they see with their own eyes that the shadow moves, and understand how the Earth turns. Explain to them at the same time why you never look at the sun.