Seasons: Skydome
Practical Activity
for 11-14
- Activity time 15 mins
Use a lamp and a transparent dome attached to a globe to show how the path of the Sun across the sky varies over the year.
Preparation
This activity works best in a darkened room.
Equipment
- Approx. 40 cm diameter globe
- A small transparent dome (eg half of a 4 cm clear plastic bauble)
- Lamp
- Blu Tack or sticky tape
- Books to adjust height of lamp (optional)
Procedure
- Use blu-tac or sticky tape to attach the dome to the globe so that it covers the UK.
- Place the globe about 1 m from the lamp (the Sun). Adjust the lamp's height so that it is the same as the globe’s equator.
- Position the globe so that the northern hemisphere is tilted away from the Sun.
- Spin the globe anticlockwise about its axis so that the reflection of the lamp appears on the base of the eastern edge of the dome, travels up the dome and sets on the western edge.
- Repeat, but this time tilt the globe's Northern Hemisphere towards the Sun (the arm of the globe may get in the way when you spin. Detach and re-attach dome as required).
Discussion prompts
- Which lasts longer: day or night?
- What season is it in the UK?
Teaching notes
This demonstration tackles the common misconception that the path of the Sun across the sky does not vary over a year. Students should see that when the northern hemisphere is tilted away from the Sun (first day of winter in the UK) sunrise to sunset takes less than half a spin, day is shorter than night and the Sun follows a low path across the sky. When the northern hemisphere is tilted towards (first day of summer in UK), the Sun follows a high path across the sky, days are longer than night and it is warmer because the sun's radiation warms the ground for more time.
You could also demonstrate the path of the Sun across the sky on the first day or spring/autumn to show that day and night lasts equal times and the Sun follows an intermediate path across the sky.
Learning outcome
Students explain why days are longer in summer and how this contributes to it being warmer.
This experiment was safety-checked in March 2020.
