created by Carl Sabanski
Equatorial Sundial Kit
Equatorial Sundial: a dial in which the dial plate is parallel to the equatorial plane and the polar-pointing gnomon is perpendicular to it.
The equatorial sundial is a universal dial and can be used anywhere in the world. All you have to do is position it correctly and it will tell you the time. The equatorial sundial is also used to draw a number of other sundials including horizontal, vertical and polar sundials. It is quite easy to make as the hour lines on the sundial are placed at intervals of 15° for every full hour.
The equatorial sundial is a very important sundial that can teach you many things and everyone should have one. Figure 1 shows the Kit that you will use to make your own equatorial sundial. There is another page that has the very easy to follow instructions.
Figure 1: Equatorial Sundial Kit (CAD)
The sundial is designed so that you can build one for the Northern or Southern Hemisphere. All you need are scissors, cardboard, glue, tape and a couple of drinking straws or wood dowel. The dial is a lot of fun to make and would be a great science project. If you would like to download a PDF file of the "Equatorial Sundial Kit" just open the door.
If you think that the sundial is too large or that it takes too many sheets of paper we have two more kits for you. This next file has small and smaller equatorial sundials. Your challenge will be to find a gnomon with a small enough diameter that the shadow is not too large. You will still need the large sundial kit if you want the instructions.
When you have completed the sundial all you have to do is set up and it will tell you solar time. Figure 2 shows you just how easy this is. All you have to do is point the gnomon to the north or south celestial pole. Because the dial plate of your equatorial sundial represents the equator the sun will be above it for half the year and below it the other half. The sun's position depends upon which hemisphere you live in. Summer in one - winter in the other. Now you can see why there is an upper and lower dial face.
Figure 2: Equatorial Sundial (CAD)
An equatorial sundial will show the time between sunrise and sunset throughout the year. Find the earliest time of sunrise and the latest time of sunset for your location. You can use the "Dialling Buddy" for this. Using a compass and ruler you can draw additional morning and evening hour lines and customize your sundial for your location. You don't even have to measure any angles. Remember that the upper dial face will show more hours than the lower. Do this before you cut out the dial.
Here's what the sundial will look like once you have finished making it. There are two different sundials shown below. They are both positioned for a latitude of 40° but one is in the Northern Hemisphere and the other is in the Southern Hemisphere. You can see the shadows of the two equatorial sundials at different times of the year.
Northern Hemisphere - June - 1:00 P.M.
Southern Hemisphere - June - 1:00 P.M.
Northern Hemisphere - December - 11:00 A.M.
Southern Hemisphere - December - 11:00 A.M.
This sundial is very easy to build and a lot of fun to use. We would like to see yours.