An indoor sundial!
The Sun Tracker is a colorful window decoration and specially-designed sticker set that helps you keep track of the Sun’s changing position.
It’s a clever tool for doing science at home or in the classroom – it’s also a beautiful window decoration that pays tribute to Kepler’s Great Stellated Dodecahedron!
Place it on your window and watch it glisten and glow. Then follow the Sun’s shadow and mark its motion with the enclosed (removable) stickers.
You will learn how the Earth moves and makes the Sun change position in the sky.
It’s “Stonehenge for your window.”
Sun Tracker User Guide
- Put the Sun Tracker on a sunny window.
- Put a sticker where the Sun Tracker’s shadow falls.
How to pick a window. Find any window where the Sun shines through at some point during the day. This is a window that faces east, south, or west.
A floor or wall where the shadow will fall. The window should allow sunlight to shine through the Sun Tracker. The sunlight will shine through the Sun Tracker on to a wall or floor and make a shadow.
Place small, removable sticky-notes to mark the position of this shadow each day. The Sun Tracker should remain in the same place during an entire year if possible!
However, if the first placement is not good for some reason, you can easily move the Sun Tracker… just make sure to remove any stickers you have placed already.
Basic Sun Tracking – Hour by Hour
Each hour – starting in the morning, once per hour, place a sticker to mark the Sun Tracker shadow location. Notice how the shadow gets shorter (closer to the window) as the Sun goes higher. You can do this basic hour-by-hour tracking every day! It’s a fun activity in itself, and it naturally leads into the more advanced usage.
Advanced Sun Tracking – Day by Day
Each day – at exactly the same time of day – place a sticker to mark where the shadow is. Notice how at the same time the next day, the Sun Tracker shadow has moved!
Make sure you write the date and time on the stickers. You need to record the times to be able to accurately track and understand the day-by-day motion of the Sun.
If it is cloudy, just skip marking for the day.
It’s likely that after a few weeks the Sun Tracker shadow will move far away from the first marked point. It is likely to move so far that the shadow will no longer be “markable.” This is perfectly normal! The Sun Tracker shadow will eventually return to the spot again. So, keep tracking!
Why do the shadows move?
The Earth moves in two main ways:
- The Earth rotates like a spinning top on an axis that goes between its north and south poles (you can think of the North Pole as the handle of the top). This daily movement is what causes day and night and makes shadows change hour-by-hour.
- The Earth travels in an orbit (a oval-shaped path through outer space) around the Sun – the orbit of the Earth causes monthly and yearly changes to the Sun’s motion and shadows.
Because of these two motions, the Sun “moves” along a slightly different path through the sky each day. The path the Sun follows depends on what part of the year it is. In summer it is a high path that causes short shadows. In winter it is a low path that causes long shadows.
Each year the motions of the Sun repeat. There are 2 Solstices and 2 Equinoxes.
Follow up activities
The Sun Tracker is like a giant, immersive sundial. You are “inside” the sundial and experience the shadows.
Winter and summer solstice. If you are marking the Sun’s movement during the winter or summer solstice you will notice that the Sun seems to stand still over a few days. This is the meaning of the word “solstice” – sun standstill!