The Solar System
Grade 4 · Science · Study Guide
Explore the sun, eight planets, and other objects that make up our solar system.
The solar system is made up of the Sun and everything that orbits, or travels around, it. The Sun is a star at the center of our solar system. It provides heat and light that make life on Earth possible. The Sun is so large that about one million Earths could fit inside it.
There are eight planets in our solar system. In order from the Sun, they are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. A helpful way to remember the order is: My Very Excellent Mother Just Served Us Nachos.
The four inner planets (Mercury, Venus, Earth, and Mars) are called terrestrial planets. They are rocky and relatively small. The four outer planets (Jupiter, Saturn, Uranus, and Neptune) are called gas giants. They are much larger and made mostly of gases.
Saturn is famous for its beautiful rings made of ice and rock. Jupiter is the largest planet in the solar system. Earth is the only planet known to support life, partly because of its liquid water and atmosphere.
Our solar system also contains dwarf planets (like Pluto), moons, asteroids, and comets. Asteroids are mostly found in the asteroid belt between Mars and Jupiter. Comets are icy objects that develop a glowing tail when they travel close to the Sun.
Key terms
- Solar system
- The Sun and all the objects that orbit it, including planets, moons, asteroids, and comets
- Orbit
- The curved path one object takes around another in space, such as a planet around the Sun
- Terrestrial planet
- A rocky, Earth-like planet; the four inner planets: Mercury, Venus, Earth, and Mars
- Gas giant
- A large planet made mostly of gas; the four outer planets: Jupiter, Saturn, Uranus, and Neptune
- Asteroid
- A rocky object smaller than a planet that orbits the Sun; many are found in the asteroid belt
- Comet
- An icy object that orbits the Sun and develops a glowing tail when it passes close to the Sun
Flashcards
- Solar system
- The Sun plus all planets, moons, asteroids, comets, and other objects that orbit it
- Orbit
- The path an object takes as it travels around another object in space
- Terrestrial planet
- A small, rocky planet; Mercury, Venus, Earth, and Mars
- Gas giant
- A large planet made mostly of gas; Jupiter, Saturn, Uranus, and Neptune
- Asteroid
- Rocky objects smaller than planets that orbit the Sun; most are in the asteroid belt
- Comet
- An icy body that orbits the Sun and forms a bright tail near the Sun
- Moon
- A natural satellite that orbits a planet
- Dwarf planet
- A round object that orbits the Sun but has not cleared its orbital path; Pluto is an example
Questions
What is at the center of our solar system?
- Earth
- Jupiter
- The Moon
- The Sun
Show answer
Answer: The Sun
The Sun is a star at the center of our solar system. All planets, asteroids, and comets orbit the Sun.
Jupiter is a terrestrial (rocky) planet.
Show answer
Answer: False
Jupiter is the largest of the gas giants, made mostly of hydrogen and helium gas. Terrestrial (rocky) planets are Mercury, Venus, Earth, and Mars.
The path a planet takes around the Sun is called its ______.
Show answer
Answer: orbit
An orbit is the curved path one object follows as it travels around another due to gravity. Earth completes one orbit around the Sun each year.
Which planet is known for its large, visible rings?
- Jupiter
- Mars
- Saturn
- Neptune
Show answer
Answer: Saturn
Saturn is famous for its spectacular ring system made of ice chunks and rocky debris orbiting the planet. While other gas giants have rings, Saturn's are the most visible.
Earth is the third planet from the Sun.
Show answer
Answer: True
The order of planets from the Sun is Mercury, Venus, Earth, making Earth the third planet. This position in the habitable zone allows liquid water to exist.
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