Space Lesson: Planets, Orbits, and the Solar System

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Updated: Mar 25, 2025

Lesson

Space is a big, mysterious place filled with stars, planets, moons, and more. It stretches far beyond what we can see with our eyes. Even though we live on Earth, we are part of a much larger neighborhood called the solar system.

Let us take a journey through space where we will learn about the planets, how they move, what they are made of, and what makes our Earth so special.

What Is the Solar System?

The solar system is made up of the sun and everything that travels around it, including:

Eight planets
Moons
Asteroids
Comets
Dwarf planets like Pluto

At the center of the solar system is the sun, which gives light and heat to all the other objects. All the planets orbit (move around) the sun.

The Order of the Planets

The planets are arranged in a specific order based on their distance from the sun. You can remember them using the phrase:

"My Very Educated Mother Just Served Us Nachos"

Order	Planet
1	Mercury
2	Venus
3	Earth
4	Mars
5	Jupiter
6	Saturn
7	Uranus
8	Neptune

Some lists include Pluto as a dwarf planet, which means it's very small and different from the main eight.

Take This Quiz:

Solar System Planets Quiz

Earth: The Water Planet

Earth is the third planet from the sun. It's special because:

It has liquid water covering most of its surface
It is the only known planet to support life
It has the right air, temperature, and gravity for humans and animals

That's why Earth is often called the "Water Planet" or the "Blue Planet".

Venus: The Evening Star

Venus is the second planet from the sun and is called the "Evening Star" because it shines brightly in the night sky. It is:

Similar in size to Earth
Covered in thick clouds
Very hot because it traps heat

Even though it looks beautiful, Venus would be too hot for humans to live on.

Mars: The Red Planet

Mars is the fourth planet from the sun and is often called the Red Planet because of its reddish color. Mars:

Has cold temperatures and dusty land
May have had water a long time ago
Is being studied by robots and probes

Many scientists believe that Mars is the best place to look for signs of life beyond Earth.

Jupiter: The Giant Planet

Jupiter is the fifth planet from the sun and the largest planet in our solar system. It is known for:

A giant red spot (a huge storm)
Dozens of moons
Being made mostly of gas

It is so big that it could fit more than 1,300 Earths inside it!

Saturn: The Planet with Rings

Saturn is the sixth planet from the sun and is famous for its beautiful rings. These rings are made of ice and rock. Saturn:

Has at least 18 moons
Is mostly made of gas
Spins very quickly on its axis

It is one of the most popular planets to observe with a telescope.

Uranus and Neptune: The Cold Giants

Uranus is the seventh planet from the sun. It's special because:

It spins on its side
It's very cold
It has a light blue color

Neptune is the eighth planet. It is:

Dark blue in color
The windiest planet
The farthest known planet from the sun

Both Uranus and Neptune are made mostly of gas and ice.

Pluto: The Dwarf Planet

Pluto used to be called the ninth planet, but now scientists call it a dwarf planet. It is:

Very small
Covered in ice
Far away from the sun

Pluto is part of a region of space beyond Neptune that has many small icy objects.

Take This Quiz:

Space and Solar System Quiz!

What Is the Asteroid Belt?

Between Mars and Jupiter, there is a region called the Asteroid Belt. It is filled with rocky objects called asteroids.

Asteroids are too small to be planets.
They are made of rock and metal.
They move around the sun, just like planets do.

Scientists study asteroids to learn about the early solar system.

Comets and Meteoroids

Comets

Comets are like dirty snowballs in space. They are made of:

Ice
Dust
Rock

They have long elliptical orbits and glow when they come close to the sun, forming a bright tail.

Meteoroids

Meteoroids are chunks of rock or metal floating in space. They often come from:

Comets
Asteroids that have broken apart

If a meteoroid enters Earth's atmosphere and burns up, we call it a meteor (a shooting star).

Take This Quiz:

Test your knowledge about Space

How Do Planets Stay in Orbit?

Planets move around the sun in paths called orbits, which are not perfect circles-they are elliptical (oval-shaped).

Two main forces work together to keep planets in orbit:

Force	What It Does
Gravity	Pulls planets toward the sun
Inertia	Makes planets want to keep moving in a straight line

Together, gravity and inertia create a balanced path that keeps planets moving around the sun instead of flying off into space or falling into the sun.