This sundial has been built for Canberra.

# Making a sundial

Construct a sundial and research the techniques different cultures use to study time.

• 14 January 2011 | Updated 17 February 2013

### You will need

To construct this sun dial you will need:

• nail or piece of dowel (approximately 20 cm long)
• piece of craftwood (20 cm x 20 cm)
• another piece of craftwood to serve as a wedge
• three brass screws
• wood glue
• compass
• protractor
• black marker
• table for Equation of Time (see below).

### What to do

1. Using the marker and the protractor, mark out the design shown in the picture above. The angle between each hour should be 15 degrees. The line representing six o'clock is parallel to the top of the board and approximately 2 cm down.
2. Ask an adult to either hammer the nail partially into the craftwood, or drill a hole and glue in the piece of dowel.
3. Attach a wedge, using screws and glue, to tilt the sundial at the required angle away from the vertical - use the table below to determine your latitude. Latitude is a measure of your location, in degrees, north or south of the Equator. For example, a sundial built for Canberra (35 degrees south of the equator) is tilted 35 degrees from the vertical, or 55 degrees from the ground.
4. Using the compass, place the sundial in the sunlight with the '12' facing south (or north if you are in the Northern Hemisphere).
5. The shadow of the nail or dowel will tell you the time. Use the table  'Equation of time' (below) to determine how many minutes you must add or subtract to accurately calculate the time.

### Equation of time table

Use the table below to adjust the time on your sundial. For example, if your sundial's shadow indicates 1.00 pm on 15 March, then the correct time is 12.51 pm (1.00 pm minus nine minutes).

5th 15th 25th
January -5 -9 -12
February -14 -14 -13
March -12 -9 -6
April -3 0 +2
May +3 +4 +3
June +2 0 -2
July -4 -6 -6
August -6 -5 -2
September +1 +5 +8
October +11 +14 +16
November +16 +15 +13
December +10 +5 0

### What is happening

Mechanical clocks were not invented until about 1200 AD. Before then, people had to use other methods for telling the time. Early civilisations used the position of the Sun in the sky to estimate the time.

Sundials use shadows cast by the Sun to measure the time. As the Sun moves across the sky, the shadow shifts its position. The equation of time helps to adjust for inaccuracies in the Earth's orbit.

Sundials come in many different forms. For example a sundial in Jaipur, India, is actually a large building. Other sundials similar to the one you made are small enough to be placed in a garden or held in your hand.

See more activities in Physical sciences activities.

Latitudes for Australian cities

 Adelaide 35° Alice Springs 24° Brisbane 27° Canberra 35° Darwin 12° Hobart 43° Melbourne 38° Perth 32° Sydney 34° Townsville 19°