Science Courses / Course / Chapter

Solar System Overview & Model

Nicholas Amendolare, Jeff Fennell
  • Author
    Nicholas Amendolare

    Nicholas Amendolare is a high school and middle school science teacher from Plymouth, Massachusetts. He has a bachelor's degree in environmental science from Worcester Polytechnic Institute and a master's degree in education from Harvard University. He has been a teacher for nine years, has written for TED-Ed, and is the founder of

  • Instructor
    Jeff Fennell

    Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

Learn the solar system definition and what our solar system consists of. Understand what defines a planet, how the solar system was formed, and objects in the solar system. Updated: 02/25/2022

Table of Contents


What is the Solar System?

A solar system is a system of stars, planets, moons, and other objects, bound together by gravitational orbit. Let us first explain that our solar system includes one sun, eight planets, more than two hundred moons, as well as many other objects. Although the solar system definition might seem simple, understanding the components, the structure, and the formation of a solar system is no simple task. For the remainder of this lesson, we will focus on our own solar system, meaning the sun-planet-moon system in which we live. But keep in mind that we live in a galaxy with millions upon millions of undiscovered solar systems, many of which could be just like our own.

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Mercury: Facts & Retrograde

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:02 Definition
  • 0:15 Formation
  • 0:46 Objects in the Solar System
  • 2:29 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Formation of the Solar System

By studying evidence found within our own solar system, as well as by observing other solar systems using telescopes, scientists have a widely-accepted hypothesis regarding how our own solar system was created. Scientists posit that about 4.5 billion years ago, a cloud of gas and dust in one of the spiral arms of the Milky Way galaxy began to spin and swirl, possibly due to the explosion of a nearby supernova. In the center of the swirl, gas and dust began to clump together, and as that clump grew, so did its gravity. Eventually, the clump grew so large, and the pressure from gravity grew so extreme, that the hydrogen atoms in the clump began to fuse into helium. Such fusion releases tremendous amounts of heat and light, and suddenly this clump of matter was no longer just a clump. It was a star, the star that today we call "the Sun."

According to scientists, our sun's gravity pulled in about 99% of the available matter in our solar system. But the remaining 1% was still swirling and spinning, trapped by the sun's gravity, and locked into orbit. This remaining matter began the same sort of clumping process, where matter clump's together, increasing its gravity, and thereby pulling in even more material. Some of these clumps grew so large that their own gravity naturally shaped them into spheres. These spheres, locked into orbit around our now-shining sun, became known as planets and moons. The smaller clumps, chunky and irregular, became known as asteroids and comets. Scientists refer to this formation process as the "nebular hypothesis."

What Does the Solar System Consist Of?

When someone asks "What does the solar system consist of?" they are usually referring to the most famous objects: the Sun, our moon, Jupiter and Saturn, etc. but to describe the solar system accurately means we must account for all objects, large and small, that live in our stellar neighborhood.

The Sun

The Sun is, by far, the largest and most massive object in the solar system. But in truth, it is a rather average star. But calling it average shouldn't make it appear any less important. The sun is the primary provider of energy for the solar system and for planet Earth. It is classified as a GV star, also known as a yellow dwarf star. It has a diameter of 865,370 miles (1.4 billion km) and is located roughly 93 million miles from Earth. To give you an idea of its size, it would take about 109 Earths, stacked on top of each other, to add up to the Sun's diameter. It would take about 1.3 million Earths, stuffed inside the sun, to fill up the Sun's volume.

A NASA telescope image of our sun.

A NASA telescope image of our sun, just one answer to the question, what does the solar system consist of?.

The fusion within the sun generates massive amounts of heat and light. Its surface temperature is about 10,000°F and its core temperature is more than 27,000,000°F. It also has a gravitational pull that is 27.9 times the strength of Earth's. Earth's acceleration due to gravity is around 9.8 m/s per second, but the Sun's is over 274 m/s per second. This means that if you allowed an object to fall on Earth for 2 seconds, it would reach a speed of about 44 mph. But if you allowed an object to fall through the sun's gravity for 2 seconds, it would reach a speed of more than 1,200 mph. But only if it survived the heat.

The Planets

Our solar system has eight planets as well as many dwarf planets. The word "planet" comes from the Greek word planetes which means wanderer. The planets were originally thought to be wandering stars, lost in the night sky above, due to their ever-changing positions. The name stuck. Today, we know our solar system has eight planets and many dwarf planets. The planets are spherical objects with strong gravitational pulls that orbit our sun in regular intervals. The closest planet is Mercury, followed by Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Asteroids & Comets

Objects that are smaller than planets are typically classified as either asteroids or comets. Asteroids are small, rocky bodies that orbit the sun. Comets are small objects made of ice and dust that orbit the sun. Because this ice tends to vaporize as comets orbit, comets have a characteristic tail, swept outward by the solar wind. In total, there are over 1 million known asteroids and roughly 3,700 known comets in our solar system.

A NASA image of the asteroid Bennu.

A NASA image of the asteroid Bennu.

Most of the solar system's asteroids and comets can be found in three distinct locations: the asteroid belt, the Kuiper belt, and the Oort cloud. The asteroid belt is a group of orbiting asteroids and comets in between Mars and Jupiter. The Kuiper belt is a similar group found beyond the orbit of Neptune. The Oort Cloud, on the other hand, is a far-off group (more shell-like than belt-like) composed of asteroids, comets, and other debris at the most distant edge of our solar system.

To unlock this lesson you must be a Member.
Create your account

Frequently Asked Questions

What is the solar system easy definition?

A solar system is a group that includes one or more suns along with planets, moons, asteroids, comets, and other extraterrestrial object. Our solar system includes one sun and eight planets.

What is the solar system for kids?

The solar system includes the Sun, the Earth, and the moon, along with seven other planets and more than 200 other moons.

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back

Resources created by teachers for teachers

Over 30,000 video lessons & teaching resources‐all in one place.
Video lessons
Quizzes & Worksheets
Classroom Integration
Lesson Plans

I would definitely recommend to my colleagues. It’s like a teacher waved a magic wand and did the work for me. I feel like it’s a lifeline.

Jennifer B.
Jennifer B.
Create an account to start this course today
Used by over 30 million students worldwide
Create an account