Our solar system consists of the Sun and eight planets. Pluto is not considered a planet, it is called a dwarf planet. The solar system is supposed to have been formed 5-5.6 billion years ago. And our planets were formed about 4.6 billion years ago.
solar system
The Solar System also includes other bodies such as moons, millions of asteroids, comets, dust grains and gases as well. Mercury, Venus, Earth and Mars are called the inner planets as they lie between the sun and the belt of asteroids. And the other four planets are called outer planets.
The Difference between Inner and Outer planets
| Inner planets | Outer planets |
| made up of rocks | made up of gases and liquids |
| also known as Terrestrial | also known as Jovian |
| lower gravity | higher gravity |
| high densities | low densities |
The inner planets are also called terrestrial planets as they are composed of rock and metal. These terrestrial planets have high densities.
The other four giants are called Jovian or Gas Giant planets. The jovian means Jupiter-like. These four planets are more massive and larger than terrestrials. These giants have a thick atmosphere which is mostly of helium and hydrogen.
Jupiter is the largest planet and mercury is the smallest planet among all of the planets. Mercury is closest to the sun.
The Sun
The sun is the star located at the center of our solar system. All the planets revolve around the sun in elliptical orbits. A ray of light from the sun takes about eight minutes to reach the earth. The sun has a surface temperature of 6000 degrees Celcius and increases to 20 million degrees Celcius in the interior.
Mercury
Mercury is the smallest and closest planet to the sun. It is 36 million miles away from the sun. A year in mercury is only 88 days. Mercury does not have any satellites.
Venus
Venus is often called as ‘Earth’s Twin’ due to their proximity in size, mass and density. It is the second closest planet to the sun.
Earth
It is the only planet that has sustainable environmental conditions for the life. It has a natural satellite (the Moon) that revolves eastward around the earth.
Mars
Mars is often called as a ‘Red planet’ due to its red color. It has two natural satellites. It is the second smallest planet after mercury in our solar system. It is the fourth closest planet to the sun.
Jupiter
It is the largest planet in the solar system. It is the fifth planet from the sun. It has natural satellites. Its surface is made up of gases like hydrogen, helium and methane. The surface of Jupiter is very cold.
Saturn
It is the second-largest planet in the solar system. It has natural satellites. It is the sixth planet from the sun. It has three rings and nine satellites.
Uranus
It orbits around the sun in a clockwise direction from east to west. It has five satellites.
Neptune
It is the eighth planet from the sun.