Solar System

Solar System Facts

What is the Solar System?

The solar system includes the Sun and all the objects that orbit around it due to its gravity. This includes things such as planets, comets, asteroids and meteoroids.

When was the Solar System formed?

The Solar System formed around 4.6 billion years ago.

solar system facts

Solar System Overview

Planets: There are eight planets in the Solar System. The four inner planets are Mercury, Venus, Earth and Mars. The four outer planets are Jupiter, Saturn, Uranus and Neptune.

Terrestrial Planets: The inner planets (or terrestrial planets) are smaller and made mostly of rock and metal.

Outer Planets: The outer planets (known as gas giants) are much larger and made mostly of hydrogen, helium and other gases.

Dwarf Planets: There are also five dwarf planets which were discovered in 2008. These planets are Pluto, Ceres, Eris, Makemake and Haumea.

Asteroid Belt: There is an asteroid belt which lies between the orbits of Mars and Jupiter; it features a large number of irregular shaped asteroids.


Earth was the Centre of the Universe

For thousands of years humans had no idea about the Solar System and believed that Earth was at the centre of the Universe.

Astronomers such as Nicolaus Copernicus, Galileo Galilei, Johannes Kepler and Isaac Newton helped develop a model which explained the movement of the planets with the Sun at the centre of the Solar System.

sun center of solar system

(Sun at center of Solar System – click to enlarge)

The Sun contains 99.86 percent of the Solar System’s known mass, with Jupiter and Saturn making up making up most of the rest. The small inner planets make up a very small percentage of the Solar Systems mass.

Amazing quick facts about the Solar System 

What is the hottest planet?

Did you know that the hottest planet isn’t the one that is closest to the Sun? Most people believe that Mercury is the hottest as it’s the closest to our burning sun.

But that’s not true. The hottest planet is actually Venus as it is covered by a really thick atmosphere, which is 100 times thicker than Earth’s atmosphere. This saves the energy of the sun instead of it escaping into space. Plus its atmosphere is mostly made up of carbon dioxide, which lets solar energy in.

interior of Venus

(The interior of Venus)

How small is Pluto?

Pluto is smaller than the USA. The greatest distance across the US in nearly 2,900 miles (4,667km). Pluto is just over 1,400 miles (2,253km) across, which is less than half the width of the US. Because of its size it is now called a dwarf planet.

Pluto facts

What are volcanoes made of?

Did you know that volcanoes aren’t just made from magma? On Earth molten rock called lava is what causes volcanoes, however on Saturn’s moon Enceladus, Neptune’s moon Triton, and others too, the thing that makes volcanoes is ice!

Rocks from Mars on Earth

There are Mars rocks on Earth that weren’t brought here by humans. Chemical analysis of meteorites found in Antarctica, the Sahara desert and other places have been shown to have originated on Mars!

These meteorites could have blasted away from Mars due to an impact, or from a huge volcanic eruption, and then later collided with Earth.

Jupiter’s Ocean

Jupiter has the biggest ocean of any planet. It has much higher levels of hydrogen and helium when it formed as opposed to Earth.

Computer models show that it is not only the largest ocean known in the solar system but it is about 24854 miles (40,000km) deep – about as deep as the Earth is around. That’s quite amazing stuff.

So those are our awesome facts about the Solar System!

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