The Planets
Learn
Our Solar System
Our solar system consists of the Sun (a star) and everything that orbits around it, including eight planets, dwarf planets, moons, asteroids, and comets. The Sun contains 99.8% of all the mass in our solar system!
The planets orbit the Sun in elliptical (oval-shaped) paths, held in place by the Sun's gravity. The closer a planet is to the Sun, the faster it orbits and the shorter its year.
☀️
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Memory Trick: "My Very Eager Mother Just Served Us Nachos" - the first letter of each word helps you remember the planets in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune!
Two Types of Planets
Inner Planets (Rocky/Terrestrial)
⚪ 🟡 🌍 🔴
- Closer to the Sun
- Smaller in size
- Made of rock and metal
- Solid surfaces you could stand on
- Few or no moons
Outer Planets (Gas Giants)
🟠 🪐 🔵 🔷
- Farther from the Sun
- Much larger in size
- Made mostly of gas and liquid
- No solid surface to land on
- Many moons and rings
Meet the Planets
⚪
Mercury
1st from Sun- Smallest planet in our solar system
- Extreme temperatures: -180°C to 430°C
- Year: 88 Earth days
- No moons
🟡
Venus
2nd from Sun- Hottest planet (465°C) due to thick atmosphere
- Rotates backwards compared to most planets
- Similar size to Earth ("Earth's twin")
- No moons
🌍
Earth
3rd from Sun- Our home! Only planet with known life
- 71% covered by liquid water
- Perfect temperature for life
- 1 moon (The Moon)
🔴
Mars
4th from Sun- Called the "Red Planet" (iron oxide rust)
- Has the tallest volcano (Olympus Mons)
- Rovers explore its surface
- 2 moons (Phobos, Deimos)
🟠
Jupiter
5th from Sun- Largest planet - 1,300 Earths could fit inside!
- Great Red Spot is a giant storm
- Gas giant with no solid surface
- 95+ moons (including Ganymede, largest moon)
🪐
Saturn
6th from Sun- Famous for beautiful, visible rings
- Would float if you had a big enough ocean!
- Second-largest planet, gas giant
- 146+ moons (including Titan)
🔵
Uranus
7th from Sun- Rotates on its side (tilted 98°)
- Called an "ice giant" - extremely cold
- Blue-green color from methane gas
- 27 known moons
🔷
Neptune
8th from Sun- Strongest winds in solar system (2,000 km/h)
- Too far to see without a telescope
- Another ice giant
- 16 known moons (including Triton)
Examples
Planet Quiz
Score: 0/8
Loading question...
Quiz Complete!
You completed the Planet Quiz!
Final Score: 0/8
Practice
Question 1: Which planet is known as the "Red Planet"?
Question 2: What is the main difference between inner and outer planets?
Question 3: Which planet is the largest in our solar system?
Question 4: Which planet is famous for its beautiful ring system?
Check Your Understanding
Key Questions
- Can you name all eight planets in order from the Sun?
- What makes Earth unique among all the planets?
- Why is Venus hotter than Mercury even though Mercury is closer to the Sun?
- What do all four outer planets have in common?
Fun Fact: A day on Venus (one complete rotation) is longer than a year on Venus (one orbit around the Sun)! Venus spins so slowly that it takes 243 Earth days to rotate once, but only 225 Earth days to orbit the Sun.
Summary
🌍
8 Planets
4 rocky inner, 4 gas/ice outer
👑
Jupiter
Largest planet
⚪
Mercury
Smallest & closest to Sun
🏠
Earth
Only planet with known life
Next Steps
- Practice the planet mnemonic until you can name them in order
- Research your favorite planet to learn more
- Move on to learn about moon phases