How well do you know the solar system? 

by Precious Cyprain
4 mins read
The solar system


The solar system consists of the sun and every other body that revolves around it bound together by a gravitational system. These include the eight planets, numerous planetary satellites (moon), asteroids, comets, dwarf planets and meteorites. The solar system is about 4.568 billion years old and is in the Milky Way Galaxy within the Orion-Cygnus arm.  

The solar system Is part of the systems in space that can be viewed with the aid of technology such as telescopes and other instruments. This part of the universe is known as the observable universe. 

Composition of the solar system  

The planetary system in the solar system consists of eight planets which are arranged in ascending order of distance from the sun. The eight planets are classified into four terrestrial planets and four giant planets. The terrestrial planets, also known as the inner solar system, are made up of rock and metal and they include Mercury, Venus, Earth and Mars.  

The giant planets, also called the outer solar system, are further divided into two namely gas giants and ice giants. The gas giant planets are made of helium and hydrogen, and they include Jupiter and Saturn. The ice giant planets are made up of ammonia, water, hydrogen sulphide, carbon dioxide and methane which are mostly volatile substances, and they include Neptune and Uranus.  

In August 2006, the International Astronomical Union (IAU) voted to remove Pluto as one of the planets and place it under another classification known as dwarf planets.  

There are nine recognized dwarf planets which include Ceres, Pluto, Orcus, Haumea, Quaoar, Makemake, Gonggong, Eris, and Sedna. There are 758 known natural satellites which include 285 planetary satellites and 473 minor planetary satellites. Many minor planets have also been discovered along with 4,586 known comets and 19 identified rounded satellites. Other small-body populations include centaurs and interplanetary dust clouds which move freely within the solar system. 

Unlike the other six planets having one or more moons, Mercury and Venus are the only planetary bodies without any moon. The gas giant planets, Jupiter and Saturn, have the highest number of moons in the solar system. Pluto, a dwarf planet smaller than our moon, also has five moons in its orbit including a very large moon that makes the planet unsteady called Charon. Asteroids also have one or more moons.  

The formation of the solar system 

About 4.5 billion years ago, the solar system was formed from the collapse of space within a large molecular cloud which consisted of hydrogen, helium and small amounts of heavier elements. After the collapse of this space called the pre-solar nebula, it began to spin faster. The gas and dust at its center began to clump together, becoming larger along with its gravity which grew bigger thereby making the hydrogen atoms in the clump fuse into helium which released large amounts of light and heat. Then this clump of matter turned into a star which we call “the sun” today.  

Congregates of leftover debris that didn’t form planets are located in certain regions in the solar system such as the asteroid belt, Kuiper belt, and Oort cloud. Several billion comets are also found in these reservoirs. The Oort cloud is a spherical shell that surrounds the solar system at a distance of 50,000 AU (astronomical units). The Kuiper belt is a thick disk-shaped zone beyond the orbit of Neptune with a distance of 30-50 AU from the sun.  

The planet-building process brought about remnants known as asteroids and comets. The asteroid belt consists of rocky asteroid bodies of different size ranges. An example is Ceres which is also classified as a dwarf planet having a diameter of 940 km.  

Some asteroids collide with planets because they move in the paths that cross the orbits of the planet. Collision of asteroids or large objects with Earth have been known to have devastating effects like the asteroid impact said to be responsible for the extinction of dinosaurs 65 million years ago.  

Comets have physical characteristics that are different from that of asteroids. They consist mainly of ice such as frozen water, carbon dioxide, methanol and carbon monoxide. Comets can be classified into long-period comets and short-period comets according to the time it takes for them to orbit the sun.


Read also: Interesting facts you didn’t know about the eight planets in the solar system

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