Ancient mariners relied on the sun’s position to navigate the vast oceans. The sun’s movement is predictable, and its position in the sky can be used to estimate the time of day. With a little practice, anyone can learn how to tell time by the sun. Furthermore, this skill can be useful in the event of a power outage or when you are lost in the wilderness.
To tell time by the sun, you first need to find your latitude. This can be done using a GPS device or a map. Once you know your latitude, you can use a sun chart to determine the sun’s position in the sky at different times of the day. Sun charts are available online or in many outdoor recreation stores. Additionally, you can use a compass to determine the sun’s direction. When the sun is in the east, it is 6 o’clock in the morning. When the sun is in the south, it is noon. When the sun is in the west, it is 6 o’clock in the evening.
To be more precise, you can use a sundial to measure the sun’s angle. A sundial is a simple device that consists of a stick or rod that is placed in the ground. The shadow of the stick will point in the direction of the sun. The length of the shadow will vary depending on the time of day. By measuring the length of the shadow, you can determine the time of day. Finally, keep in mind that the sun’s position can be affected by clouds and other weather conditions. Therefore, it is important to use a sun chart or compass to get the most accurate results.
Identifying the Sun’s Position
Observing the sun’s position in the sky is crucial for timekeeping. Here’s a detailed guide to identifying the sun’s position:
**Locate the Northern Hemisphere:** If you’re in the Northern Hemisphere, the sun will appear in the southern half of the sky.
**Sunrise and Sunset:** In the Northern Hemisphere, the sun rises in the east and sets in the west. At sunrise, it’s located at an azimuth (horizontal angle) of 90 degrees east, and at sunset, it’s at 90 degrees west.
**Noon Position:** At noon, the sun reaches its highest point in the sky. In the Northern Hemisphere, it’s directly overhead, so its azimuth is 180 degrees (due south), and its altitude (angle above the horizon) is 90 degrees.
**Midday Line:** The midday line is an imaginary line in the sky that connects the points directly above and below the sun at noon. It divides the sky into eastern and western halves.
**Seasonal Variations:** The sun’s position changes slightly throughout the year due to the Earth’s tilt on its axis. During the Northern Hemisphere’s summer months, the sun is higher in the sky and follows a longer path across the horizon, resulting in longer daylight hours.
| Sunrise Azimuth | Sunset Azimuth | Noon Altitude | Noon Azimuth | |
|---|---|---|---|---|
| Northern Hemisphere | 90° East | 90° West | 90° | 180° (Due South) |
| Southern Hemisphere | 90° West | 90° East | 90° | 180° (Due North) |
Understanding Sun’s Daily Path
The sun’s daily path, or analemma, is a figure-eight shaped curve that the sun traces in the sky over the course of a year. This curve is caused by the tilt of the Earth’s axis and the Earth’s orbit around the sun. The sun’s highest point in the sky occurs at noon, and its lowest point occurs at midnight. The sun’s position in the sky at any given time can be used to determine the time of day.
Factors Affecting Sun’s Daily Path
Several factors influence the sun’s daily path, including:
- Latitude: The sun’s daily path varies with latitude. In the Northern Hemisphere, the sun is higher in the sky during the summer months and lower in the sky during the winter months. The opposite is true in the Southern Hemisphere.
- Longitude: The sun’s daily path also varies with longitude. The sun is higher in the sky in the morning in the east and lower in the sky in the evening in the west. This is because the sun moves across the sky from east to west.
- Time of year: The sun’s daily path changes throughout the year due to the Earth’s orbit around the sun. The sun is highest in the sky during the summer months and lowest in the sky during the winter months.
By understanding the factors that affect the sun’s daily path, you can use the sun to determine the time of day with reasonable accuracy.
| Month | Approximate Time of Sunrise | Approximate Time of Sunset |
|---|---|---|
| January | 7:00 AM | 5:00 PM |
| April | 6:00 AM | 6:00 PM |
| July | 5:00 AM | 7:00 PM |
| October | 7:00 AM | 5:00 PM |
Note: These times are approximate and will vary depending on your location and the specific day of the year.
Using a Clock Face or Sticks
The clock face is the traditional method of displaying the time, with numbers representing the hours (1 to 12) and smaller lines indicating the minutes (0 to 60). The hour hand is shorter and thicker than the minute hand. The second hand is the longest and thinnest, moving around the face once per minute.
Using Sticks
Another simple way to tell time using the sun is by creating a sundial. This involves placing a stick upright in the ground and observing the shadow it casts. The shadow will move as the sun travels across the sky, and the time can be determined by the angle of the shadow. To achieve accuracy, ensure that the stick is perpendicular to the ground and that it is in a clear area where the shadow will not be obstructed.
| Time of Day | Shadow’s Direction |
|---|---|
| Morning | West |
| Noon | Straight down |
| Afternoon | East |
The length of the shadow also provides an approximate indication of the time. A shorter shadow indicates that it is closer to noon, while a longer shadow suggests earlier or later hours.
Making a Sun Dial
To make a sun dial, you will need the following materials:
- A stick or pole
- A flat surface
- A compass
- A protractor
- A pencil
First, you need to find a flat surface that is exposed to the sun for most of the day. Then, you need to drive the stick or pole into the ground so that it is vertical. Next, you need to use the compass to find true north. Once you have found true north, you need to use the protractor to draw a line from the stick to the north. This line will be the 12 o’clock line.
Now, you need to divide the remaining 360 degrees of the circle into 12 equal parts. To do this, you can use a protractor to mark off 30-degree increments around the circle. Once you have marked off the 12 equal parts, you can use the pencil to draw lines from the stick to each of the marks. These lines will represent the hours of the day.
Finally, you need to label the lines with the appropriate hours. The 12 o’clock line should be labeled with a “12”, the 1 o’clock line should be labeled with a “1”, and so on. Once you have labeled the lines, your sun dial is complete.
| Hour | Angle from North |
|---|---|
| 12 | 0° |
| 1 | 30° |
| 2 | 60° |
| 3 | 90° |
| 4 | 120° |
| 5 | 150° |
| 6 | 180° |
| 7 | 210° |
| 8 | 240° |
| 9 | 270° |
| 10 | 300° |
| 11 | 330° |
Estimating Time by Shadows
Observing the length and direction of shadows can provide a rough estimate of the time. In the Northern Hemisphere:
| Time of Day | Shadow Direction and Length |
|---|---|
| Sunrise | Shadow points due east and is longest. |
| 9-11 AM | Shadows shorten and point northeast. |
| 12-2 PM | Shadows are shortest and point straight down (if no obstructions). |
| 3-5 PM | Shadows lengthen and point northwest. |
| Sunset | Shadow points due west and is longest. |
In the Southern Hemisphere, the shadow directions are reversed (e.g., sunrise shadows point west).
Additional Tips:
- Use a vertical object like a stick or a tree to create a distinct shadow.
- Mark the endpoint of the shadow at regular intervals (e.g., every 15 minutes) to track its movement.
- Be aware of obstacles that may block the shadow or distort its length.
- Consider the season and time zone when making estimates, as the sun’s angle varies throughout the year.
- Remember that this method provides an approximation of the time and may not be accurate to the minute.
Recognizing Sun’s Patterns
To effectively tell time by the sun, it’s crucial to recognize the patterns of its movement throughout the day. The sun’s position relative to the horizon varies with both the time of day and your location on Earth. Here are some key patterns to note:
Sunrise and Sunset
The sun rises in the east and sets in the west. Knowing the general direction of sunrise and sunset in your location can help you orient yourself and estimate the approximate time of day.
North-South Axis
During its daily movement, the sun travels along a rough north-south axis. At noon, the sun will be approximately directly overhead for locations on the equator. For locations north or south of the equator, the sun will appear higher in the sky during its respective summer months and lower during winter months.
Clockwise Movement
As the sun rises, it moves clockwise around the horizon. This means that the sun will appear to move from east to south, then west, and finally back to north as the day progresses.
Shadow Length
The length of shadows cast by objects can provide an indication of the time of day. As the sun rises, shadows become shorter until noon, when they are at their shortest. After noon, shadows begin to lengthen again.
Equinoxes and Solstices
There are two equinoxes and two solstices throughout the year that mark significant changes in the sun’s position and path. During equinoxes, the sun is directly overhead at the equator, resulting in roughly 12 hours of daylight and 12 hours of darkness worldwide. During summer solstices, the sun reaches its northernmost or southernmost point, leading to the longest and shortest days of the year, respectively.
Time Zones and Daylight Saving Time
Time zones and daylight saving time can affect the relationship between the sun’s position and the time indicated by clocks. To accurately tell time by the sun, it’s important to consider your local time zone and whether or not daylight saving time is in effect.
Using a Stick and Compass
This method requires a stick and a compass. Plant the stick vertically in the ground and mark the direction of the shadow it casts using a small stone or stick. Wait for about 15 minutes. The new shadow will intersect the first mark, forming a line. Bisect this line to find the north-south axis. The point where the stick meets the ground will represent the north pole. Now, face the north pole and hold the compass in your hand, adjusting the needle until it aligns with the north-south axis you created.
Determining the Time
The angle between the north-south axis and the hour hand of the compass represents the hour. Each hour is equivalent to 15 degrees. To determine the exact time, divide the angle by 15. For example, if the angle measures 60 degrees, subtract 12 to account for the midday mark, and divide by 15. The result is 3:00 PM.
| Angle | Time |
|---|---|
| 0-15 | 12:00 PM |
| 15-30 | 1:00 PM |
| 30-45 | 2:00 PM |
| 45-60 | 3:00 PM |
| 60-75 | 4:00 PM |
| 75-90 | 5:00 PM |
| 90-105 | 6:00 PM |
Note that this method is only an approximation and may vary based on the accuracy of the shadow measurements and compass readings.
Employing a Time Equation Calculator
A time equation calculator is a tool that can assist you in determining the Sun’s exact position in the sky and adjusting your timepiece accordingly. You can locate various online time equation calculators by searching for them. To use a time equation calculator:
1. Enter Your Location
Input your latitude and longitude coordinates into the calculator. You can use a GPS device or online tools like Google Maps to determine your coordinates.
2. Select the Date and Time
Specify the date and time for which you need the time equation. The time equation varies throughout the year, so it’s crucial to use the exact date and time.
3. Compute the Time Equation
The calculator will calculate the time equation based on your input. The time equation is expressed in minutes. A positive value indicates that the Sun is ahead of your timepiece, while a negative value means it’s lagging behind.
4. Adjust Your Timepiece
To correct your timepiece, add the time equation to the current time if it’s positive. If the time equation is negative, subtract it from the current time. This will give you the correct local time based on the Sun’s position.
5. Consider Daylight Saving Time
Remember that daylight saving time can affect the time equation. Adjust your calculations if daylight saving time is in effect.
6. Choose the Right Calculator
There are several time equation calculators available online. Select one that is accurate and user-friendly.
7. Verify Your Calculations
After completing the calculations, verify the result by comparing it with an established time source, such as the National Institute of Standards and Technology (NIST).
Reading a Shadow Clock
Shadow clocks, also known as sundials, are ancient timekeeping devices that rely on the movement of the sun’s shadow to indicate the time. Here’s a step-by-step guide to reading a shadow clock:
Materials:
- A straight stick or rod
- A flat surface
- A marker or chalk
Procedure:
- Plant the stick: Insert the stick upright on the flat surface.
- Mark the stick’s shadow: At different intervals throughout the day, mark the end of the stick’s shadow on the surface.
- Connect the marks: Draw lines connecting the marks to form a pattern of intersecting lines that resemble a clock face.
- Label the lines: Use a marker to label the lines with the corresponding hours.
- Align the stick with north: The shadow’s shortest length occurs at noon, when the sun is highest in the sky. Mark this spot as north.
- Divide the lines into hours: Depending on the time of year, the lines between the hours will be longer or shorter.
- Check the shadow: To tell the time, simply note where the shadow falls on the clock face.
- Adjust for daylight saving: During daylight saving time, adjust the clock face by one hour ahead.
- Using the shadow’s length to estimate the time:
| Shadow Length (compared to stick length) | Approximate Time |
|---|---|
| Less than 1/4 | Noon or midnight |
| 1/4 to 1/2 | 9:00 AM or 3:00 PM |
| 1/2 to 3/4 | 10:00 AM or 2:00 PM |
| 3/4 to 1 | 11:00 AM or 1:00 PM |
Calibrating the Sun as a Clock
Calibrating the sun as a clock involves determining the Sun’s specific trajectory in the sky for your location and time of year. This process requires attention to detail and accurate observation, as the Sun’s position changes gradually throughout the day and varies with the seasons.
To effectively utilize the Sun as a timepiece, you must first identify its path across the sky. Start by locating the Sun’s position at midday when it reaches its highest point in the sky. This point is known as the meridian. It is recommended to observe the Sun’s position for several days around midday to gain a clear understanding of its daily movement.
Next, determine the Sun’s position at sunrise and sunset. These points mark the beginning and end of the day, respectively. You can use a compass or smartphone app to find the cardinal directions (north, south, east, and west) and observe the Sun’s location relative to these points.
Once you have established the Sun’s trajectory for your location, you can create a simple sundial to indicate the time. You can use a stick, a tree branch, or a vertical object as a gnomon (the part of the sundial that casts a shadow). By aligning the gnomon with the Sun’s path at midday and marking the shadow’s position, you can create a reference point for dividing the day into equal intervals.
| Time | Sun’s Position in Sky |
|---|---|
| 6:00 AM | In the east, approximately 15° above the horizon |
| 9:00 AM | In the southeast, approximately 45° above the horizon |
| 12:00 PM (Midday) | Directly overhead, at the highest point in the sky |
| 3:00 PM | In the southwest, approximately 45° above the horizon |
| 6:00 PM | In the west, approximately 15° above the horizon |
How To Tell Time By Sun
The sun moves across the sky from east to west during the day. The position of the sun in the sky can be used to tell the time. The higher the sun is in the sky, the later it is. The lower the sun is in the sky, the earlier it is. In the northern hemisphere, the sun is highest in the sky at noon and lowest in the sky at midnight. In the southern hemisphere, the sun is highest in the sky at midnight and lowest in the sky at noon.
To tell the time by the sun, you need to find a place where you can see the sun. You can use a sundial, a watch, or a compass to help you find the sun. Once you have found the sun, you need to determine its position in the sky. You can do this by looking at the angle of the sun above the horizon. The higher the angle, the later it is. The lower the angle, the earlier it is.
You can also use the length of the sun’s shadow to tell the time. The longer the shadow, the earlier it is. The shorter the shadow, the later it is. You can use a stick or a ruler to measure the length of the sun’s shadow.
People Also Ask
How do you tell time using a sundial?
A sundial is a device that uses the sun’s position in the sky to tell the time. It consists of a flat plate with a pointer that casts a shadow. The shadow moves as the sun moves across the sky, and the position of the shadow indicates the time.
How do you tell time using a watch?
A watch is a device that uses a mechanical or electronic mechanism to measure time. Watches typically have a dial with hands that indicate the hours, minutes, and seconds. The hands move as the mechanism advances, and the position of the hands indicates the time.
How do you tell time using a compass?
A compass is a device that uses a magnetic needle to align itself with the Earth’s magnetic field. The needle always points north, and the direction of the needle can be used to determine the time. In the northern hemisphere, the sun is east of north at sunrise and west of north at sunset. In the southern hemisphere, the sun is west of north at sunrise and east of north at sunset.
