Using the rotation of the earth and knowing the conformation of the cardinal points with respect to sunrise and sunset, you will be able to create, in a basic way, a compass to orient yourself in a general way.
Develop these Key Competencies:
- Critical Thinking
- Systems Thinking
- 1 stick or branch of at least 1 meter
- 4 small stones or objects (coins, marbles, etc.)
- 1 chalk
- 1 rope of approximately 40cm
CAUTION: Protect yourself from the sun. Never, for any reason, look directly at the sun, even with glasses. Wear sunglasses and sunscreen.
- Drive the stick or a branch into the ground, taking care to do it in a flat environment so that a visible shadow is projected.
- At the tip of the shadow, mark with a stone the moment you start the process.
- Wait about 10 or 20 minutes for the tip of the shadow to move a few centimetres. The longer the stick, the "faster" your shadow will move.
- After waiting, mark the new position of the point of the shadow with another stone.
- Draw a line between the two marks for an approximate East-West direction. You can use string, chalk, or both for greater precision. The first point will always indicate the West, and the second the East, at any time of the day and in any part of the Earth.
- By drawing a second line perpendicular to the first, the approximate North-South direction will be obtained, with which you will be practically oriented and able to go where you want. NOTE: Tilting the stick to achieve a more convenient shadow due to its size or direction does not influence the accuracy of this method. Thus, whoever walks on slopes or with much vegetation does not need to look for smooth terrain. All required to mark the two points of the shadow is a small flattened space no more significant than the palm. The stick can be planted on any of its edges. Nor is it essential to use a bar or a branch for this operation; the same result is obtained with any fixed object.
- Identify all cardinal points. Check your position with a compass.
- What is the difference between magnetic north and geographic north?
The sun rises in the east and reaches its maximum height when it indicates the south direction; finally, it descends until it sets, at which point it marks the west direction, but very rarely does it go exactly east and west. The sun rises in the east, pulling slightly to the south, and sets in the west, pulling slightly to the north. The declination, that is, the angle it forms with each of the two cardinal points, varies according to the year's seasons and the hemisphere where we live. In this case, the information indicated here deals with the northern hemisphere.[MW1]
Did you know…
Magnetic north is changing all the time, while geographic north is fixed. Your solar compass points to the geographic north.
Equal shadows method. It is a more precise variant of the shadow point method and can be used at latitudes below 66º and any time of the year.
1. Plant a stick or branch vertically on the ground, taking advantage of a flat enough space so that the projected shadow, which must measure at least 30 cm, can be clearly distinguished. Mark the tip of the shade with a stone, twig, etc. This should be done for 5 to 10 min. Before noon (solar time -> so no daylight saving time if this applies to your country).
2. Draw a semicircle using the shadow as the radius and the base of the stick as the centre. This tracing can work with a string, a shoelace, or a second stick.
3. As we approach noon. (solar time), the shadow becomes shorter. After noon, it lengthens until it crosses the arch.
4. Draw a straight line between the two marks, the East-West line.
Although, as we said, this version of the shadow point method is more precise than the first, it is subject to two conditions:
a) It should be done around noon.
b) To carry it out, the observer has to watch the shadow and conclude the third stage at the exact moment when the tip of the shadow reaches the arc.