Day and night simulator

What this simulator shows

Earth spins once a day, and that spin makes day and night. The big picture looks down on the North Pole, with sunlight coming from the left, so the left half of Earth is in daytime and the right half is in night. A coral pin marks a person at 40° north, about as far north as New York City. Press Spin or drag the Earth around, and the clock shows the person's time of day. Two smaller pictures show the person's sky, looking south, and a stick in the ground seen from above, with its shadow.

• Sunrise happens as the person is carried from the night side into the day side; sunset is the other edge.
• Earth spins toward the east, so the Sun appears to rise in the east and set in the west.
• Shadows are longest near sunrise and sunset, when the Sun is low, and shortest at noon.
• North of the tropics, the noon Sun is in the south, so the noon shadow points north.

Why spinning it helps

From the ground it really does look as if the Sun travels across the sky, so the idea that we are the ones moving is a big step. Linking the view from space with the view from the ground, at the same moment, is what makes it click. The shadow stick adds a second clue children can check outside on a sunny day.

Common misconceptions

Young children often think the Sun goes around Earth, or that night happens because the Sun goes behind a hill or the Moon covers it. Another common idea is that the Sun is directly overhead at noon. Outside the tropics it never is: at 40° north it reaches about 50° above the horizon around the March and September equinoxes, which is why the shadow never disappears. The clock here is Sun time, so noon means the Sun is at its highest. Real clocks can differ by an hour or more because of time zones and daylight saving time.

A 10-minute day and night activity

• Ask: "What makes it get dark at night?" Listen to the child's idea first.
• Press Spin and pause it when the person is at the edge of the light. Ask whether that is sunrise or sunset.
• Step through the day with + 1 hour. Write down the shadow length every 2 hours.
• Ask: "When was the shadow shortest? Which way did it point?"
• If it is sunny, go outside and mark a real shadow at two different times.

Where this fits in school

• US, grade 1: NGSS 1-ESS1-1 asks students to describe patterns of the Sun, Moon and stars that can be predicted, such as the Sun rising and setting.
• US, grade 5: NGSS 5-ESS1-2 asks students to show daily changes in the length and direction of shadows, and day and night.
• England, Year 3: pupils find patterns in the way the size of shadows changes. Year 5: pupils use Earth's rotation to explain day and night and the Sun's apparent movement across the sky.

Learning more

Earth and space science is on Eurekami's skill map, with short lessons that draw diagrams like this one live and explain them out loud. A few daily practice questions keep ideas like sunrise, sunset and shadows fresh.