The Solar System is made up of the Sun and the objects that orbit around it. There are eight planets in our Solar System, and all of them revolve around the Sun. In this lesson, you’ll learn the names of the planets, how they are classified, and key facts that are easy to understand and remember.
What Is the Solar System?
The Solar System is a gravitationally bound system consisting of the Sun (a star) and all the objects that orbit it, including planets, dwarf planets, moons, asteroids, and comets. Among these objects, the eight planets are the largest bodies that orbit the Sun directly.
The 4 Terrestrial Planets (Inner Planets)
The inner planets are also called terrestrial planets. They are made mostly of rock and metal and have solid surfaces.
- Mercury
- Venus
- Earth
- Mars
Key facts and examples:
- Mercury: Mercury is the closest planet to the Sun and can reach temperatures of about 430°C during the day.
- Venus: Venus is the hottest planet because its thick atmosphere traps heat.
- Earth: Earth is the only planet known to support life.
- Mars: Mars is called the Red Planet because of its reddish surface.
The 4 Gas Giants (Outer Planets)
The outer planets are much larger and are mostly made of gas and ice. They do not have solid surfaces like the inner planets.
- Jupiter
- Saturn
- Uranus
- Neptune
Key facts and examples:
- Jupiter: Jupiter is the largest planet in the Solar System.
- Saturn: Saturn is famous for its beautiful ring system.
- Uranus: Uranus rotates on its side, unlike most other planets.
- Neptune: Neptune is the farthest planet from the Sun and has very strong winds.
Dwarf Planets
A dwarf planet orbits the Sun and is round in shape but has not cleared its orbit of other objects. In 2006, Pluto was officially classified as a dwarf planet.
- Pluto
- Eris
- Haumea
- Makemake
- Ceres
Pluto: Pluto is a dwarf planet located in the Kuiper Belt and is smaller than Earth’s Moon.
Other Bodies in the Solar System
Not all objects in the Solar System are planets.
- The Sun: a star at the center of the Solar System
- The Moon: Earth’s natural satellite
The Sun: The Sun provides light and heat for all the planets.
The Moon: The Moon orbits the Earth and affects ocean tides.
Planetary Vocabulary
- Orbit: the path a planet follows around the Sun
- Gravity: the force that pulls objects toward each other
- Atmosphere: the layer of gases surrounding a planet
- Axis: an imaginary line a planet spins around
Last Updated on January 28, 2026
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it’s fun learning about planets!
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Planets are round