Earth, Space, and the Solar System
Our place in space
Earth in the universe
Earth is a planet that orbits the Sun. The Sun is a star, and planets are objects that orbit stars. Together, the Sun and the objects around it make up the solar system.
Scale matters
Space is very large. Distances are often so huge that normal units like kilometers become inconvenient.
Important solar system objects
The solar system includes the Sun, planets, moons, asteroids, and comets. Earth has one Moon. Some planets have many moons. Planets do not make their own light; they reflect sunlight.
Space vocabulary
What does Earth orbit?
Earth revolves around the Sun.
Correct answer: The Sun
Star vs. planet
Star
- Produces its own light and heat
- Example: the Sun
- Usually very hot
Planet
- Orbits a star
- Reflects light
- Example: Earth
Day, night, and seasons
Earth rotates on its axis once about every 24 hours, causing day and night. Earth also orbits the Sun, and the tilt of Earth helps create seasons.
What causes day and night?
Earth spins, so different parts face the Sun at different times.
Correct answer: Earth's rotation
Name one object in the solar system besides the Sun and planets.
Many objects besides planets orbit in the solar system.
Correct answer: A moon, asteroid, or comet.
What causes Earth to have seasons?
The tilt changes how sunlight hits different parts of Earth during the year.
Correct answer: Earth's tilt as it orbits the Sun.