If you ask which direction the Sun rises, many people would easily answer: “The Sun rises in the East and sets in the West.” However, not everyone knows how to determine which direction is East and which is West. There are various ways to find directions, but using the Sun is the simplest method. You can easily identify East, West, South, and North.
Method 1: Observe the Sunrise and Sunset
From a young age, we all learned a basic lesson about determining direction:
- In the morning: The Sun rises in the East.
- In the evening: The Sun sets in the West.
However, this is not entirely accurate. The Sun’s position at sunrise and sunset changes throughout the year, following the seasons: Vernal Equinox, Summer Solstice, Autumnal Equinox, and Winter Solstice. The Sun only rises and sets exactly in the East and West during the Vernal and Autumnal Equinoxes.
- On days of the Summer Solstice (June 21 or 22), the Sun rises in the Northeast and sets in the Northwest.
- On days of the Winter Solstice (December 21 or 22), the Sun rises in the Southeast and sets in the Southwest.
You can determine directions using the Sun. (Illustrative image).
Method 2: Determining Direction with a “Stick and the Sun” (Owen Doff Method)
Owen Doff was a British pilot who traveled the world and discovered a method for determining direction.
He experimented over 1,000 times from various locations and achieved near-accurate results using just a stick in sunlight. In his honor, this method is named after him: Owen Doff.
Here’s how it works:
- Stick a stick into the ground when it’s sunny, perpendicular to the ground. The tip of the shadow is referred to as T.
- After about 15 minutes, the shadow will have changed. The new tip of the shadow will be referred to as D.
- Connecting points T and D gives a straight line indicating East-West; point T indicates West, and point D indicates East. Once East/West is established, North/South can be easily determined.
Method 3: Using a Clock with Hour Hand
Place a clock on a flat surface, horizontally, and turn the clock face so that the short hand A (hour hand) aligns with the shadow of a stick placed outside. Draw the angle bisector OI of angle AOB (B is the number 12, and O is the clock’s axis).
- If it’s morning, the angle bisector OI will indicate South (clockwise).
- If it’s afternoon, the angle bisector OI will indicate North (counterclockwise).
Note: If you are in the Southern Hemisphere, you will need to reverse this.
The principle of this method is based on the Sun’s rising and setting relative to the Earth, creating a circular path around the Earth over 24 hours. The hour hand of a clock completes one circle in 12 hours, meaning that in the same period, the hour hand describes an arc greater than twice.
Conversely, if we take the North-South direction and bisect the arc described by the hour hand (with the clock’s position as previously described), we will find the direction of the Sun’s position.
This method may not be very accurate, with potential errors reaching several degrees. The main reason is that the clock is placed parallel to the horizon, while the Sun’s daily path only lies on the horizontal plane at the poles. At other latitudes, this path creates different angles with the horizon, which can be greater than 90 degrees (at the Equator). Therefore, this method can only yield accurate results in areas close to the poles!
In addition to determining direction using the Sun, other methods involve wind and practical experience.
* Determining Direction by Wind:
Vietnam is located in the “Monsoon Asia” region with two main types of winds: the Northeast Monsoon and the Southwest Monsoon. The Northeast Monsoon lasts from October to April, blowing from the Northeast to the Southwest. The Southwest Monsoon lasts from May to October, blowing from the Southwest to the Northeast.
- To find out the wind direction, observe the tops of trees, grass, flags, etc.
- Hold some dust or small paper scraps and drop them to see which way the wind carries them.
- Wipe one finger clean, suck it in your mouth for about 10 seconds, then hold it up; the side that feels cold is the direction from which the wind is blowing.
* Determining Direction by Experience:
- In bad weather, when the Sun, Moon, and stars are not visible, and without a compass, you can estimate direction by looking at the trunk of a tree. The side that is more moist indicates North since the Sun does not shine on this side. From there, you can deduce other directions.
- Choose an old tree or architectural structure to examine; if one side of the tree trunk has thick, rough, dark bark, that side is likely North. For architectural structures, the side that grows more moss, is darker, and damp is also the North side.
- When encountering a tree stump, look at the growth rings; the side with more densely packed rings indicates North.
- In the forest, if you find a tree stump with ants, the ant nest is usually on the South side.
- If you come across a church standing alone, the main entrance will always face West.
