The Sun is a bright star that gives Earth light and warmth. Young learners see the Sun every day, so it is a great way to begin learning about space and weather. The Sun helps us know when it is daytime and makes many outdoor activities possible.
Plants, animals, and people all depend on the Sun in important ways.
The Sun looks small in the sky, but it is much bigger than Earth. Its light travels through space and reaches our planet, helping plants grow and keeping Earth warm enough for life. The Sun also helps create shadows and can make things feel hotter on sunny days.
Learning about the Sun helps students connect science to the world they see around them.
Understanding The Sun
The Sun produces energy deep in its core. There, pressure is enormous because the Sun’s gravity squeezes matter inward. Hydrogen atoms join together to make helium.
This process is called nuclear fusion. A tiny amount of matter changes into energy during fusion. That energy begins as intense radiation.
It takes a very long time to move from the core through the crowded layers of the Sun. When it finally leaves the surface, it travels through space as sunlight. The sunlight that reaches Earth left the Sun about eight minutes earlier.
Gravity gives the Sun its round shape and holds nearly all the material in the solar system close to it. The Sun’s pull keeps Earth moving in its orbit instead of flying away into space. The Sun is made mostly of hot gas called plasma.
Plasma can carry electric currents and create powerful magnetic fields. Sometimes these fields release bursts of particles into space. This flow is called the solar wind.
Earth has its own magnetic field, which directs many of these particles away. Near the poles, some particles can collide with gases high in the atmosphere and produce auroras, the colored lights seen in polar skies.
The amount of solar energy reaching a place changes during the day and through the year. Sunlight is strongest when it arrives more directly. At midday, the Sun is usually higher in the sky, so its rays spread over a smaller area of ground.
In the morning and evening, the rays arrive at a slant and spread out more. Earth’s tilted axis causes the seasons. A hemisphere tilted toward the Sun gets more direct sunlight and longer days.
This is why summer is warmer. The changing energy from the Sun drives the water cycle. It causes water to evaporate, helps form clouds, and provides energy for much of Earth’s weather.
Students can observe the Sun’s effects without looking at it. Watch how a shadow changes length and direction during a day. A short shadow usually means the Sun is high in the sky.
Notice that pavement, dark clothing, and sand can feel warmer because they absorb more solar energy. Solar panels use sunlight to move electric charges and make electricity. The Sun gives off invisible ultraviolet radiation too.
This can damage skin and eyes, even on cloudy days. Use shade, protective clothing, and sunscreen when needed.
During an eclipse, normal sunglasses are not safe. Only approved eclipse viewers protect eyes from the Sun’s concentrated light.
Key Facts
- The Sun is a star at the center of our solar system.
- The Sun gives Earth light and heat.
- Daytime happens when our part of Earth faces the Sun.
- Plants need sunlight to grow.
- The Sun can make shadows when it shines on objects.
- Never look straight at the Sun because it can hurt your eyes.
Vocabulary
- Sun
- The Sun is the bright star that gives our world light and warmth.
- Star
- A star is a huge glowing ball in space that makes its own light.
- Sunlight
- Sunlight is the light that comes from the Sun.
- Warmth
- Warmth is the heat we feel from the Sun.
- Shadow
- A shadow is a dark shape made when light is blocked.
Common Mistakes to Avoid
- Thinking the Sun is a planet, but that is wrong because the Sun is a star that makes its own light.
- Thinking the Sun only helps people, but that is wrong because plants and animals need sunlight too.
- Thinking shadows appear without light, but that is wrong because shadows form when sunlight is blocked.
- Looking straight at the Sun, but that is wrong because the Sun is too bright and can hurt your eyes.
Practice Questions
- 1 A plant gets sunlight for 3 days and then for 2 more days. How many days of sunlight did it get in all?
- 2 There are 4 children playing outside in the sunshine, and 3 more join them. How many children are playing in the sunshine now?
- 3 Why is the Sun important for plants, animals, and people? Give one reason for each.