Our solar system is approximately 4.6 billion years old and is made up of planets, dwarf planets, moons and other astronomical objects that all orbit the sun. It was formed by a gravitational collapse of a giant molecular cloud.
In the middle of our solar system there is the sun which takes up a huge 99.8% of the systems mass. The suns gravity pulls the surrounding planets towards it and keeps them in orbit.
The closest planets to the sun, known as the inner planets or terrestrial planets are Mercury, Venus, Earth then Mars. These planets are mainly composed of rock and metal. The outer planets or “Gas Giants” are Jupiter, Saturn, Uranus and Neptune. Jupiter and Saturn are primarily hydrogen and helium where as Uranus and Neptune and mainly ices like water, methane and ammonia. These two planets are often referred to as “Ice Giants”.
Our solar system has five dwarf planets, Ceres, Pluto, Haumea, Makemake and Eris. Dwarf planets share some similarities to planets but the main difference is a dwarf planet has not cleared the neighbourhood around its orbit. Pluto recently had its class changed to dwarf planet as its orbit crosses Neptune a much larger planet and it also shares an orbit with the Kuiper belt.
Facts about the Solar System
- Our solar system is located in the Milky Way Galaxy
- An asteroid belt is located between the orbits of Jupiter and Mars
- There is a region of asteroids and comets called the Kuiper belt that is just beyond the orbit of Neptune
- Venus is the hottest planet in our solar system, Neptune is the coldest
- Jupiter is the largest planet, Mercury is the smallest
- Four planets in our solar system have rings. The Gas Giants Jupiter, Saturn, Uranus and Neptune.
- There is over 160 known moons in our solar system
- Earth takes one year to orbit the sun, Mercury is closest so it takes 88 days while Neptune being the farthest takes 164 years
- The majority of planets and some of the moons are surrounded with atmospheric gases