A Brief Introduction to Solar System

I am sure that most of you have seen our sun and moon and few of you have seen other planets. But did you know anything at all about our solar system. Solar system is a very wide topic. In this post I will briefly describe only the sun and planets within our planetary system.

What is a planetary system?

According to wikipedia a planetary system is a set of non-stellar bound by gravity in or out of orbit around a star or star system.

Our Solar System

By WP – Planets2008.jpg, CC BY-SA 3.0,

Our planetary system is called the solar system and it has eight planets orbiting the sun. The number of planets changed through the time as the definition of the planet changed. Now there are eight planets orbit the sun and they are 1. Mercury 2. Venus 3. Earth 4. Mars 5. Jupiter 6. Saturn 7. Uranus and 8. Neptune

The Sun

The sun is the star and the center of the solar system. It is the main source of energy of the earth. Diameter of the sun is 1.39 million km and the mass is 1.9885*1030kg. The mass is about 330,000 times that of earth. Most of the suns mass consists of hydrogen and there is a small percentage of helium as well. Sun is about 4.6 billion years old. The core temperature is 1.57*107k and the surface temperature is 5772k.

The solar system is divided into two parts and they are inner solar system and outer solar system. The two regions are divided by an asteroid belt. The inner solar system consists of terrestrial planets including Mercury, Venus, Earth and Mars.

The inner planets have some common features. They have a dense compositions and the planets have few or no moons.


By NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington – NASA/JPL.Edited version of Mercury in color – Prockter07.jpg by jjron (cropped to square)., Public Domain,

Mercury is the nearest planet to the sun. It is the smallest among the 8 planets and also it takes the shortest time to orbit sun. It is named after the Greek god Hermes which translate into Latin as Mercurius. The diameter is about 4880 km and the mass is about 3.3022*1023 kg. The surface temperature changes from 80k to 700k.


By NASA/JPL-Caltech – (Image) (Summary), Public Domain,

Venus is the second planet of the solar system situated between mercury and earth. It is named after the Roman goddess of love and beauty. It is the second brightest object in the night sky after moon. The diameter is 12,103.6 km and the mass 4.8675*1024 kg. Venus has a mean surface temperature of 737k (464 0C). The atmosphere consists of mostly Carbon Dioxide(96.5%) and Nitrogen (3.5%).


Earth is the third planet situated between Venus and Mercury and the only planet known to have life on it. The diameter of the earth is 12,742 km and the mass is 5.972*1024. Earth has one moon. The atmosphere consists of Nitrogen, Oxygen, Carbon Dioxide and many more gases.



Mars is the fourth planet and the last planet of the inner solar system. It is the second smallest planet in the solar system. The planet is named after the Roman god of war but in common it has been called as the ” Red planet” due to the iron oxide prevalent which gives its reddish color. The diameter of the planet is about 6771 km.

Mars is the last planet of the inner solar system. Then comes the outer solar system. The planets in the outer solar system have common features as well. All of them are giant planets. And they have many moons too. There are four planets and all of them have rings. But only the Saturn’s rings are visible to the earth. They are situated in a great distance from the sun many volatile compounds such as water and ammonia are present in higher percentages.


The first planet of the outer solar system is Jupiter. Named after the Roman god of thunder, it is visible to the naked eye. The composition of the Jupiter is 90% hydrogen and 20% helium and there are traces of methane, water vapour, ammonia and carbon and the mass of the Jupiter is 1.8982*1027 kg. The planet has 79 moons and four of them are found by Galileo hence they are called Galilean moons. They are Io, Europa, Ganymede and Callisto.


The next planet is Saturn and it is named after the Roman god of wealth. It is the second largest planet in the solar system. The planet is famous for its rings which consist of countless small particles ranging from micrometers to meters. The rings mostly made out of ice particles. They are not visible to the naked eye but they can be spotted easily using a telescope. Saturn has 82 moons and the largest of them is Titan. The atmosphere of the planet is 96.3% atomic hydrogen and 3.25% helium and traces of ethane, methane, phosphine and propane are detected. The clouds are formed from ammonia crystals. The surface temperature of the Saturn is about -1390c.

Fun Fact : Both Jupiter and Saturn are called “Gas Giants” while Uranus and Neptune are called “Ice Giants”


By NASA/JPL-Caltech – (image link) (image link), Public Domain,

The seventh planet of the solar system is Uranus and it is named after Greek god of the sky. It is the third largest planet in the solar system and has 27 moons and they have been named after the characters in William Shakespeare’s plays. Uranus also has planetary rings just like Saturn but they are made of extremely dark particles. Also the rings are very hard to spot. Uranus does not have a defined solid surface. The atmosphere is made out of hydrogen and helium. In comparison to other giant planets in the solar system the atmosphere is bland. The surface temperature is about -2130c


Neptune is the last planet in the solar system named after the Roman god of sea. Neptune is not visible to the naked eye and unlike other planets it was not found by observation but with the help of mathematical prediction. Like other giants Neptune’s atmosphere consists of hydrogen and helium. the surface temperature is about -2180c. Neptune has 14 moons and Triton is the largest of them.

I believe that this article has been productive to you and in the next article I will be posting about the other objects in our planetary system. Thank you for reading.

2 replies on “A Brief Introduction to Solar System”

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