Optics Mag is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Read more.

How Many Planets Are in the Solar System? What You Need to Know!

Last Updated on

solar system

There are eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. There are also dwarf planets such as Pluto, but they don’t count as full-fledged planets.

If you’re interested in learning more about the planets, keep reading. We’ll give you a quick overview of each one so that you can start exploring the solar system for yourself and see all the wonders it holds.

telescope divider 2

The Eight Planets In the Solar System

1. Mercury

Mercury is the closest to the Sun. It is very hot there and has no atmosphere. Known as the “iron planet,” Mercury is very small and dense. As such, it has a very weak gravitational pull.

planet mercury
Image Credit: Vadim Sadovski, Shutterstock

2. Venus

Venus is the second planet from the Sun and is often called Earth’s sister planet. That’s because it is very similar to our own world in size, mass, and density. However, Venus has a very different climate. It is much hotter than Earth, with temperatures reaching up to 847 degrees Fahrenheit. The atmosphere of Venus is also very dense and acidic.

partial view of Planet Venus
Image Credit: Artsiom P, Shutterstock

3. Earth

Earth is the third planet from the Sun and is the only planet that is known to support life. It has an abundance of water, air, and land. The gravity on Earth is just right for humans and other creatures to live comfortably.

the earth with a far away star
Image Credit By: GooKingSword, Pixabay

4. Mars

Mars is the fourth planet from the Sun and is often called the “red planet.” That’s because its surface is covered in rust-colored rocks and dust. Mars has a thin atmosphere and is very cold. It also has the tallest mountain in the solar system, Olympus Mons.

planet mars
Image Credit: joshimerbin, Shutterstock

5. Jupiter

Jupiter is the fifth planet from the Sun and is by far the largest of them all. In fact, it’s so big that it could fit 1,300 Earths inside it. What’s more, Jupiter also has a very strong gravitational pull. The planet is mostly made of gas and has a large red spot on its surface.

planet Jupiter
Image Credit By: GustavoAckles, Pixabay

6. Saturn

Saturn is the sixth planet from the Sun and is best known for its beautiful rings. These rings are made of ice and dust particles. Saturn is mostly made of gas, like Jupiter. However, it is much smaller than Jupiter and has a weaker gravitational pull.

planet saturn
Image Credit: Vadim Sadovski, Shutterstock

7. Uranus

Uranus is the seventh planet from the Sun and is unique because it rotates on its side. This gives it an unusual appearance. Uranus is made of gas and ice and has a very thin atmosphere.

3D rendition of planet Uranus
Image Credit: 3dFLasH, Shutterstock

8. Neptune

Neptune is the eighth and final planet from the Sun. It is very similar to Uranus in size, composition, and appearance. Neptune has a very faint ring system and a very cold climate.

view of planet Neptune from space
Image Credit: buradaki, Shutterstock

telescope divider 2 What Is the 9th Planet Called?

While technically not a planet, the dwarf planet Pluto is often considered the ninth planet from the Sun. What makes a “planet” has been a topic of debate for years, but in 2006, the International Astronomical Union (IAU) created an official definition. According to this definition, a “planet” must satisfy three conditions. It must:

  • orbit around the Sun
  • be massive enough to have its own gravity and essentially be round in shape
  • have cleared out its orbit of smaller objects
planet pluto
Image Credit: buradaki, Shutterstock

By these standards, Pluto does not qualify as a planet because it has not cleared out its orbit. It shares its orbit with other objects, including the much larger Neptune. In fact, there are probably many more than nine planets in the solar system if we include all the dwarf planets.

Other objects in the solar system that are sometimes considered planets include Ceres, which is the largest object in the asteroid belt, and Eris, which is larger than Pluto.

However, neither of these objects has cleared out its orbit, so they are not technically planets according to the IAU definition. There may be other objects in the solar system that fit the definition of a planet, but we have not yet discovered them.

The solar system also contains many smaller objects, including asteroids, comets, and meteoroids. These objects are often referred to as “minor planets.” The largest asteroid is 2 Pallas, which is about 339 miles in diameter.

And the largest comet is C/2014 UN271, which has a nucleus about 80 miles across. Most meteoroids are much smaller than either asteroids or comets and are usually no more than a few meters in size.

telescope divider 2

Final Thoughts

The solar system is an amazing place full of fascinating objects to explore. We hope this article has helped you to understand a little bit more about our place in the universe. Now that you have a better understanding of the solar system, don’t hesitate to go out and learn more about the planets and other objects that call it home.

Featured Image Credit: Vadim Sadovski, Shutterstock

About the Author Robert Sparks

Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.