How does a sundial work - A sundial determines the time accurately according to the alternate positions of the sun in the sky. It does so with the help of a flat round plate and a thin stick called a gnomon.
In order to understand how does a sundial work, let us first understand how the sun casts a shadow of the objects whenever it changes its position in the sky.
For convenience, it is believed that the sun moves in the sky, but we all know that it is our Earth that rotates around its axis.
For every degree that the Earth moves, the sun changes its position for one degree in the sky.
Likewise, the sun covers 1 degree in four minutes, 15 degrees in one hour, and for 360 degrees, it takes the whole day.
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Now, when the sun changes its positions every 24 hours, that shadow cast by the gnomon also changes, therefore lining up with the hour lines outside the circular plate.
In this way, a sundial will tell you the time according to where the shadow is cast by the gnomon stick.
Now that you know how does a sundial work, it’s time we get into the details of how YOU can use one effectively.
How to use a sundial? - How does a sundial work?
By following these simple steps, you can master using a sundial in no time!
- Point your sundial and place it on a flat horizontal surface. Keep it in an open and unshaded area to get accurate results.
- Place the gnomon according to your location I-e north, south, east, or west.
- After setting up your location, look for where the shadow falls on your sundial. Use the markings and the plate as a regular clock.
- Determine your longitude within your time zone with respect to the Greenwich Mean Time (GMT). This will also help you in pointing out the center of your time zone.
- For each hour at GMT that you’re ahead or behind, the center of your time zone will be shifted to 15 degrees longitude to East and West, respectively.
- Know about the apparent solar time, which is time-dependent on your longitude. Also, remember that for every degree rise in the longitude at east or west, subtract or add four minutes to the sundial reading, respectively.
- Have complete information about the Daylight saving time in your region to get the clock time. In case of any effect, simply add or subtract one hour to the sundial time.
- Also, make sure to get the basic adjustments made by the sun as depending upon the time of the year, the length of the day always changes. Therefore, configure the Equation of time to find out the right time.