Sun, Shadows, and Time – Build a Simple Sundial

 

☀️ Sun, Shadows, and Time – Build a Simple Sundial

Before smartphones, watches, or even clocks, humans still needed to tell the time. And how did they do it? With the oldest timekeeping device known to civilisation — the sundial.

This summer, why not blend some sunshine with science and build your very own sundial? It’s a brilliant way to explore astronomy, geometry, and history — and a perfect hands-on project for students, families, or curious minds of any age.

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🕰️ What Is a Sundial?

A sundial uses the position of the sun in the sky to cast a shadow, which then tells the time. As the Earth rotates, the position of the sun changes, moving the shadow across the dial face.

The basic parts are:

• A gnomon (pronounced “noh-mon”) — the part that casts the shadow

• A dial or base — marked with hour lines or numbers

Fun fact: The angle of the gnomon should be equal to your latitude for the sundial to work accurately.

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🛠️ How to Build a Simple Paper Plate Sundial

What You’ll Need:

• A paper plate

• A pencil or straw

• Blu-tack or tape

• A compass or compass app

• A sunny spot

• A watch (just for setup)

Instructions:

1. Poke a hole in the centre of the plate and insert the pencil upright — this is your gnomon.

2. Secure it with tape or blu-tack underneath.

3. Take it outside on a sunny day and place it on level ground.

4. Use your compass to align the plate so the pencil points north.

5. At each hour, mark the shadow tip on the plate and label it (12pm, 1pm, etc.)

6. By the end of the day, you’ll have a working sundial!

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🧪 The Science Behind the Shadow

Your sundial works because:

• The Earth rotates from west to east

• The sun appears to move across the sky from east to west

• The gnomon’s shadow moves in a predictable arc

• The shadow is shortest at solar noon, when the sun is highest

This is a great opportunity to introduce:

• Diurnal motion

• Time zones and solar vs clock time

• Latitude and Earth’s axial tilt

• Seasons and the Sun’s changing path

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🔍 Experiment Ideas

For GCSE Physics or Astronomy:

• Build sundials in different orientations — what happens if it’s not level or not facing north?

• Compare shadow lengths over several days — how does the Sun’s altitude change?

• Measure the angle of the shadow and use trigonometry to calculate the sun’s height.

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🧠 Why This Project Works

This is one of those rare experiments that blends:

• Astronomy (Earth’s motion, solar time)

• Maths (angles, geometry, trigonometry)

• Geography (latitude, Earth-Sun relationship)

• History (ancient Egyptian, Greek and Roman timekeeping)

• Practical observation and record-keeping

It's engaging, easy to personalise, and perfect for KS3, GCSE Science, Physics, and even A-Level discussions about the motion of celestial bodies.

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🎓 Learn Science and Astronomy With Us

At Philip M Russell Ltd, we turn everyday experiences into powerful learning moments. Whether it’s measuring shadow angles or exploring planetary motion, our 1:1 tuition combines theory with real-world observation — both in person and online.

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📅 Now enrolling for September in Science, Physics & Astronomy
Lab, classroom or Zoom — practical, personal, and full of wonder.
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