Equatorial Sundial (20 points)
Activity:
Learn to make an equatorial sundial to track the daytime hours. This activity is
based on the activity given on this link:
https://skyandtelescope.org/observing/how-to-make-a-sundial/
Details:
Please check out the link below for some very interesting information:

How Sundials Work

Horizontal sundials are the ones that have a readout face (or sundial’s face) with
the numbers on it parallel to the ground. Easy to use – but tricky to design and
build. See picture below:
Equatorial sundials are called that because the sundial’s face with the numbers on
it is parallel to Earth’s equator. A very simple design! See picture on the next page.
But it suffers from one drawback. Depending on the season, the gnomon’s (pencil)
shadow might fall either on the top or the bottom (underside) of the readout face.
In our activity, the face is made of translucent paper and so it’s easy to see the
shadow on the top and read the time even when it’s on the underside.
Materials
1. Sundial template (given on the last page)
2. Scissors
3. Transparent tape
4. Long sharpened pencil (a straw can also be used)
5. Sheet of cardboard such as a cereal box cardboard (optional)
Procedure
1. Take a printout of the sundial template. Use the Northern Hemisphere
template if you live in the northern hemisphere (or the Southern Hemisphere
template if living in the southern hemisphere).
2. Find your approximate latitude. You can simply use a search engine, for
example, “Google”, to find the latitude for your city, or use the following
link to find it:

Latitude Finder

3. Cut and fold the printout according to directions printed on it.
4. Push the pencil point/straw through the center of the small circle. The pencil
should be perpendicular to the sundial’s face (not to the base) after you are
done.
5. If the pencil topples over, then try taping the whole thing to another piece of
paper or to a sheet of cardboard. Cereal boxes can also be used as cardboard.
6. Turn the sundial so that the pencil points due north (or due south if you live
in the Southern Hemisphere). You can use a compass or a map to determine
the proper direction, or you can just orient the sundial so that its shadow
agrees with your local time. (Don’t forget to add one hour to your sundial
time to match the time on your watch/computer if you’re on daylight-saving
time.)
7. Now the sundial is ready, and you can watch the shadow on the sundial
change as the Sun moves from east to west over the course of the day.
(5 points)
8. Post pictures of your sundial showing two different times (preferably
morning and afternoon times) on the same day. You must also mention
which times are these. (2 points)
Questions
1. List all the disadvantages/drawbacks of a sundial. (3 points)
2. For an equatorial sundial, what are the angles of the gnomon (pencil) w.r.t.
the ground at both poles and at the equator? (3 points)
3. During which time of the year one can have a complete 24-hour sundial
clock at the north pole? (2 points)
4. At which latitude/s, we can use an equatorial sundial as a horizontal one? (2
points)
5. What are the best and the worst times of the year to use an equatorial
sundial? (3 points)
25
30
35
40
45
50
55
12 11 10
9
8
7
6 a.m.
1 2
3
4
5
6 p.m.
4.
latitude line.
Fold along best
Northern Hemisphere Sundial
1. Cut in from edge of paper along dotted lines. Stop at solid lines.
2. Fold along solid horizontal line with line on outside. Crease, then open flat again.
3. Fold along solid vertical lines with lines on outside. Crease, then open flat again.
4. Select the latitude line closest to your latitude. Fold with line outside, crease,
and fold again with line on inside.
5. Tape the paper together as shown at right.
6. Insert a sharp pencil point-first through the small circle at top center.
Remove pencil and reinsert it with the eraser first.
7. If needed for stability or durability, tape the whole thing to a sheet of cardboard.
8. Turn the sundial so the pencil points due north, as determined by a map or a compass.
9. If you can’t find north, orient the sundial so that it agrees with your clock.
(Subtract one hour from the clock time if you’re on daylight-saving time.) 3. Fold here.
3. Fold here.
1. Cut here. 1. Cut here.
4. Fold along best
latitude line.
✂
2. Fold here. ✂
5. Tape here.
5. Tape here.
25
30
35
40
45
50
55
25
30
35
40
45
50
55
12 1 2
3
4
5
6 p.m.
11 10
9
8
7
6 a.m.
4.
latitude line.
Fold along best
Southern Hemisphere Sundial
1. Cut in from edge of paper along dotted lines. Stop at solid lines.
2. Fold along solid horizontal line with line on outside. Crease, then open flat again.
3. Fold along solid vertical lines with lines on outside. Crease, then open flat again.
4. Select the latitude line closest to your latitude. Fold with line outside, crease,
and fold again with line on inside.
5. Tape the paper together as shown at right.
6. Insert a sharp pencil point-first through the small circle at top center.
Remove pencil and reinsert it with the eraser first.
7. If needed for stability or durability, tape the whole thing to a sheet of cardboard.
8. Turn the sundial so the pencil points due south, as determined by a map or a compass.
9. If you can’t find south, orient the sundial so that it agrees with your clock.
(Subtract one hour from the clock time if you’re on daylight-saving time