Solar System Facts

Scientists are learning more about our solar system every day. As we send new missions into space, we are gathering information that is added to our knowledge.

Our solar systems contain an immense number of objects. The Sun, our star, is at the center and is surrounded by planets, dwarf planets, moons, asteroids, gas, comets, and dust. To date, our solar system contains:

Our Sun contains 99.8% of the mass of the entire solar system, with the gas giant planet, Jupiter, containing almost all of the remaining mass.

Solar System Facts for Kids

  • Our Solar System has 8 Planets
  • It’s 4.6 billion years old
  • The Solar System is part of the Milky Way
  • 8 planets and 5 dwarf planets orbit the sun
  • Mercury is the smallest planet, and Jupiter is the biggest
  • The Sun is a star – a source of light and heat
  • Only the moon has been physically visited by humans in our Solar System

The Order of the Planets

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (Dwart Planet)

Here’s a great way to remember them

My Very Easy Method Just Speeds Up Naming Planets


Mercury is the closest planet to the Sun and the smallest planet in the Solar System. It has no atmosphere and no water. Also, it’s the fastest planet! It travels at 50km/31 miles per second.

It’s the planet with the most craters. Mercury’s weak atmosphere means it is vulnerable to meteor impacts. As a result, Mercury’s surface has crater impacts, making it look like our Moon.

One year in Mercury is only about 88 Earth days. It has no moons and some extreme temperature changes. It gets up to 800 °F (427 °C) during the day, but it gets down to -269 °F (*173 °C) at night.


Venus is named after the Roman goddess of love and beauty. After the Moon, it’s the second-brightest natural object in the night sky.

A Venus day is longer than a year. Venus takes longer to make one orbit around the Sun than it does to spin once on its axis. It takes 243 Earth days to rotate once and exactly 224.7 Earth days to complete one orbit of the Sun.

It’s very similar to Earth in both size and material. Temperatures on the planet reach 460°C/480°F. A wide variety of volcanoes and craters can be found on the surface of Venus.


Planet Earth, third from the sun, is the only planet with oxygen in the atmosphere, water on the surface, and life.

Earth is the fifth-biggest planet and has one natural satellite, the Moon.

All planets, except the Earth, were named after Roman and Greek gods and goddesses. The circumference of Earth is 24,901 miles, and about 70% is covered with water.


The planet is named after the Roman God of war. It’s the fourth planet from the sun in our solar system.

Mars is also called the ‘Red Planet.’ A chemical called iron oxide is present in the rocks and soil, giving it its unique color.

Mars is the second smallest after Mercury. With a diameter of 6,791 kilometers, it’s half the size of Earth. On Mars, you can jump 3x higher than you can on Earth


Jupiter is the largest planet in our solar system. It’s 318 times bigger than Earth.

One of Jupiter’s most familiar features is the Great Red Spot. This is an anticyclonic storm that’s been around for at least 350 years.

One of Jupiter’s moons, Europa, may be able to support life in an ocean underneath its icy surface.


Saturn is the sixth planet from the Sun and the second-largest planet in our solar system. It’s well known for its ring system.

It’s a gas giant just like Jupiter, Neptune, and Uranus

It’s made mostly of hydrogen and has 150 moons and smaller moonlets. One of those moons, Titan, is the second-largest in the solar system.


Uranus is 2.88 billion km from the Sun. It takes 84 years to orbit the Sun once.

There is no water on Uranus, but gasses make it appear blue. Uranus has 27 moons the biggest is called Miranda.

Because Uranus orbits on its side, its seasons are very different from ours. Winter and summer take 21 years at each pole.


It’s named after the Roman god of the sea. Neptune is the furthest planet from the sun.

It’s the smallest gas giant and a year on Neptune lasts 165 Earth years.

Neptune’s atmosphere is mostly hydrogen and helium, with a little methane.

It has an active climate. Storms whip through its upper atmosphere at high speeds. The planet has 14 moons.

Voyager 2 passed by the planet in 1989. It sent back the first close-up images of the Neptune system.

Solar System Quiz

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