Solar System Facts for Kids

Solar system planets

Understanding how the solar system works can help you better understand your world. Whether you have an interest in the sun and the stars, or you want to get a head start on the school year with some astronomy, studying the solar system is fascinating.

What Is the Solar System?

The solar system is the sun and the objects that orbit the sun. This can include planets, such as Earth, stars, asteroids and moons. According to NASA, the solar system is shaped like an egg, which is also described as elliptical. Did you know that everything in our solar system is in orbit around the sun?

The bigger an object in space is, the more gravity is has. Because the sun is so large, it attracts all the other objects in the solar system to it, but the space outside the solar system also tries to pull the planets away. This keeps them balanced between space and the sun, each in its path being pulled from each side.

Planets

The solar system is made up of eight main planets. Four of the planets are located in the inner solar system and four in the outer solar system. However, there are dwarf planets that lie within the solar system as well.

Inner Planets

  • Mars
  • Earth
  • Venus
  • Mercury

Outer Planets

  • Neptune
  • Uranus
  • Saturn
  • Jupiter

Fun Facts About the Planets

  • The inner planets are called terrestrial planets and are made up of rock and metal.
  • The outer planets are known as "gas giants" and are much larger than the terrestrial planets.
  • Mercury is the closest planet to the sun while Neptune is the planet farthest from it.
  • Mercury was also demoted to a "dwarf" planet, making it the smallest of the eight planets.
  • Venus is close to Earth's size, but is made up of carbon dioxide. The surface of the planet is 462 degrees Celsius.
  • Jupiter is the largest planet in the solar system and is made up of hydrogen and helium.

Stars

The center of the solar system, the sun, is actually a large star.

Fun Facts About the Sun

  • The sun is a yellow dwarf star.
  • The temperature is 5,500 degrees Celsius.
  • The sun is so large that about about one million Earths could fit inside it.
  • The sun makes up 99.86 percent of the solar system's mass.
  • It takes approximately eight minutes for light from the sun to reach Earth.

Fun Facts About Other Stars

  • There are about 200 billion stars in the Milky Way Galaxy.
  • There are different types of stars.
  • Red dwarf stars are smaller than the sun and burn very slowly, which means they are not very bright.
  • Blue giant stars are large and burn their fuel quickly. They are very bright and shine across great distances. When they finally burn out, they explode in a supernova.
  • The largest star in our galaxy is VY Canis Majoris.

Belts

Kuiper Belt

  • The Kuiper Belt is located beyond Neptune and the sun. It is made up of small frozen bodies.
  • Dwarf planets live in this belt, including Pluto, Haumea and Makemake.
  • Pluto is the largest object in the belt. Pluto was originally thought to be a planet, but the fact that it is part of this belt made scientists reclassify it as a dwarf planet.
  • New Horizons is the first spacecraft launched into space to study Kuiper. It is expected to arrive in July of 2015.

Asteroid Belt

  • The asteroid belt is located between Mars and Jupiter.
  • The belt is made up of irregular-shaped objects called asteroids.
  • Four of the larger asteroids are called Vesta, Ceres, Pallas and Hygia.
  • Ceres is considered a dwarf planet.
  • The belt is made up of many other objects from large asteroids to tiny particles.
  • So far, scientists have found about 90,000 asteroids in the asteroid belt.

Comets and Asteroids

Many people confuse comets and asteroids, but they are different.

Comets

  • Comets are made up of rock and ice.
  • They are originally shaped like balls, but as they approach the sun they heat up and trail gas and debris behind them in a fiery "tail."
  • You can see comets from earth.
  • Comets are thought to originate from the outer solar system.

Asteroids

  • Asteroids are similar to big rocks.
  • Some asteroids have small companion moons.
  • Large asteroids are called planetoids.

Moons

Earth's Moon

  • Earth's moon helps stabilize the planet; otherwise, Earth would wobble on its axis.
  • The moon also regulates Earth's tidal rhythms.
  • The moon orbits the Earth and the Earth orbits the sun.
  • The moon is about 239,000 miles away.
  • The moon spins at the same time the Earth spins, so those on planet Earth only ever see one side of the moon. The first humans landed on the moon July 20, 1969.

Moons of the Solar System

  • Mars has two small moons named Deimos and Phobos. There is a possible third moon as well.
  • Mercury and Venus do not have moons.
  • There are more than 170 moons in the solar system.
  • Saturn has 62 known moons orbiting it.
  • Jupiter also has at least 62 moons, but they are very small moons.
  • Pluto's two moons are called Charon and Nix.

Studying the Solar System Is Fun

The solar system is vast and much of it is still to be discovered. Understanding how the planets interact with each other and the sun is a first step to understanding the vastness of the universe. What lies beyond the Milky Way Galaxy is yet to be discovered.

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Solar System Facts for Kids