Today presenter Evan Davis learns the arts of 'natural navigation'
Could you find your way around without the use of a map or any instruments? Natural Navigator Tristan Gooley explains how to avoid getting lost using nature as your only guide.
It surprisingly easy to determine direction without the aid of instruments and only by reference to natural clues.
Using these simple clues to work out which way you stand, before you reaching for the map or GPS, sharpens the senses and brings the world to life.
If you know the time and season, you can figure out the direction of the sun
Once you understand the sun's arc it is possible to use it to find direction.
For example, in the UK the sun rises in the northeast in midsummer, in the east in spring and autumn and in the southeast in midwinter.
For everyone north of the Tropic of Cancer, including all of Europe and mainland United States, the sun is always due south when highest in the sky, when is true midday.
With practice it is possible to work out what it is doing at any time during the day and from anywhere in the world.
Mid-morning in March in the UK? It is halfway between dawn and midday so it must be close to halfway between east and due south, it will be close to southeast.
THE SKY AT NIGHT
Stars circle about the Pole Star as the earth rotates
A similar technique as used with the sun can be used with the moon, but it takes a bit of practice.
The easiest way to understand how to use the stars to find your way is remembering that if a star is overhead your destination, then it is pointing the right way.
Most stars appear to move and so will not stay over the same place for long, but Polaris, the North Star, sits steadfastly over the North Pole and so will always point north.
The stars in a part of the sky known as the "celestial equator", move constantly from east to west but they always rise due east and set due west.
Orion's Belt is very close to the celestial equator and so wherever you are in the world, it can be used as an accurate guide to east or west when it is close to the horizon.
It is not always easy to see the heaviest side of a tree
Using nature to find direction is possible without help from the sky, because of the influence of the sun and weather on the ground.
Little of what we see in nature is symmetrical and natural navigation is often about spotting subtle differences.
Trees, like all green plants, need sunlight to grow and so their growth can be used to deduce where most of the sunlight is coming from. The 'heaviest' side of isolated trees in the UK will normally be the southern side.
Mosses and lichens are quite fussy and prefer certain levels of moisture and sunlight, which means that they grow unevenly on each side of buildings and trees.
Their patterns often vary from place to place, but once deciphered are consistent over large areas. North-facing roofs near where you live may have lots of moisture-loving green moss, whereas the south-facing ones may have colonies of golden lichen that are able to thrive in the sun.
It is even possible to find your way from puddles and bare earth. The sun reaches different parts of the ground more easily than others, which means that two sides of a path often reveal a clue: if one side is dry and dusty and the other is wet and muddy then it is time to solve the puzzle of where the sun has been and then use this to find direction.
It is not just the sun that leaves footprints, but the wind too, which combs the tops of trees and each day moves clouds in a way that can be helpful.
The wind can even be used just from the feel on your face and the buffeting sound in your ears.
By Tristan Gooley, author of The Natural Navigator, published by Virgin Books.