Sun, stars, shadows, and Earth's systems (grade 5) · lesson

The sun is a star

💡 The sun is a star that looks brighter than the others only because it is much closer to us.

Stars make their own light. The sun is a star too.

Many stars are bigger and brighter than the sun. They look like tiny dots because they are very, very far away.

The moon is closest to Earth. The sun is much farther. Other stars are farther still.

🧠 How to think about it

Think of two flashlights. The near one looks brighter, even if both are the same. Distance changes how bright a light looks.

star: a huge ball of hot gas that makes its own light

🔗 How Does Our Sun Compare With Other Stars? · NASA Space Place ↗

Day, night, and the stars we see

💡 Earth spins once a day, which makes day and night, and it travels around the sun once a year, which changes the stars we see.

Earth spins like a top. It turns all the way around once a day. The half facing the sun has day. The half facing away has night.

So when it is noon in one place, it is night on the other side of Earth.

Earth spins toward the east. So the sun seems to rise in the east and set in the west.

Earth also moves around the sun once a year. At night we look out into space. As Earth moves, we face different stars. That is why some stars show up only in winter.

🧠 Let's work it out

Picture a ball with a lamp on one side.
Spin it slowly.
Each spot turns into the light, then out of it.
The sun is not moving. The ball is.

What do you think comes next?

rotate: spin around
orbit: travel around something in a path

Shadows

💡 Shadows point away from the sun and get longer when the sun is low in the sky.

A shadow forms where something blocks the sunlight.

Shadows always point away from the sun. In the morning the sun is in the east, so shadows point west.

When the sun is high, near noon, shadows are short. When the sun is low, in the morning or late afternoon, shadows are long.

🧠 Let's work it out

Find the sun first.
The shadow goes the opposite way.
Then ask how high the sun is.
Low sun means a long shadow.

What do you think comes next?

shadow: a dark shape where light is blocked

Where Earth's water is

💡 Almost all of Earth's water is salty ocean water, and most fresh water is frozen in ice.

Think of all of Earth's water as 100 cups. About 97 cups are salty ocean water.

Only about 3 cups are fresh water. About 2 of those cups are frozen in glaciers and ice sheets near the poles.

Less than 1 cup is liquid fresh water in lakes, rivers, and under the ground. That is the water people use most.

🧠 How to think about it

To find most of the fresh water, first remove the salt water. Then compare what is left: 2 cups of ice is more than 1 cup of liquid.

fresh water: water that is not salty
glacier: a huge, slow-moving body of ice

🔗 Where Is Earth's Water? · USGS Water Science School ↗

Earth's four spheres

💡 Earth's land, water, air, and living things are four systems that act on each other all the time.

Scientists split Earth into four big parts called spheres.

The geosphere is rock and land. The hydrosphere is water. The atmosphere is air. The biosphere is all living things.

The spheres act on each other. Tree roots (biosphere) split a rock (geosphere). Wind (atmosphere) blows sand that wears down rock (geosphere).

🧠 Let's work it out

Name each thing in the story, then sort it.
Tree is living, so biosphere.
Rock is land, so geosphere.
Wind is moving air, so atmosphere.

What do you think comes next?

geosphere: rock and land
hydrosphere: water
atmosphere: air
biosphere: living things