Solar System
  Introduction : The solar system consists of eight planets that revolve
  around the Sun, satellites of the planets, and a large number of small bodies
  which are comets and asteroids. Each planet revolves around the sun in its own
  orbits at its own speed. Pluto was considered the smallest planet but now it
  is not recognized anymore as a planet.
  The solar system has been classified into two categories. They are the inner
  solar system and the outer solar system.
  The inner planets are closer to the Sun and they are smaller in size as
  compared to the outer planets. The inner solar system comprises Sun, Mercury,
  Venus, Earth, and Mars. These are also referred to as terrestrial planets.
  The other four Jupiter, Saturn, Uranus, and Neptune are in the outer solar
  system. These four are massive in size and are often referred to as giant
  planets.
  Sun : The Sun is the star at the centre of the solar system. It was
  born 4.6 billion years ago and it was formed from a giant rotating cloud of
  gasses and dust known as the solar Nebula. It is a nearly perfect ball of hot
  plasma. It is by far the most important source of energy for life on Earth.
  Its diameter is about 1.39 million kilometres. Its mass is about 330,000 times
  that of Earth. Roughly three-quarters of the Sun's mass consists of hydrogen,
  the rest is mostly helium with oxygen, carbon, neon, and iron. Its
  gravitational force holds the entire solar system.
  Mercury : Mercury is the smallest and closest planet to the sun. It is
  also called swift planet because it completes its revolution in 88 earth days.
  The geological features of Mercury consist of lobed ridges and impact craters.
  Being closest to the Sun Mercury’s temperature is as high as 450 degrees
  Celsius in the mornings and nights are freezing cold. 
  Venus : Venus is the second closest planet to the sun and is also said
  to be the hottest planet in our solar system. It has a toxic atmosphere that
  always traps heat. Venus is the brightest planet and hence called the morning
  star. Its surface is covered with clouds, craters, mountains, and lava plains.
  Venus is named after the Roman Goddess of love and beauty. 
  Earth : The third planet in the solar system is Earth. It is the
  largest inner planet. Earth is the only planet in our solar system where life
  is possible. It is called the blue planet because 70% of the earth's surface
  is covered with water. This planet has only one natural satellite which is the
  Moon.
  Mars : Mars is the fourth planet from the Sun. It is called the red
  planet because of the presence of iron oxide. It has geological features
  similar to Earth. Mars is named after the Roman God of war.
  Jupiter : It is the largest planet in our solar system. Jupiter has a
  strong magnetic field. Jupiter is rich in hydrogen and helium gas and so it is
  also called a gas giant planet. Jupiter has four rings.
  Saturn : Saturn is the sixth planet of the solar system. The beautiful
  rings around the planet are made up of bits of ice, rock, and dust. Saturn’s
  atmosphere is quite like that of Jupiter because it is also largely composed
  of hydrogen and helium. This planet is named after the Roman God of
  agriculture and wealth.
  Uranus : Uranus is the seventh planet of the system. Uranus is called
  an ice giant planet because its layer is made of ice, hydrogen, helium, and
  methane.  Uranus's core is colder than the other giant planets. Uranus
  looks blue in color because of the presence of methane. 
  Neptune : Neptune is the eighth and the farthest planet from the sun in
  the solar system. Neptune’s atmosphere is composed of helium, hydrogen,
  methane, and ammonia. It is the only planet in our solar system which is found
  by mathematical prediction. Neptune is named after the Roman God of the
  sea. 
  Comets and asteroids : They are small celestial bodies that rotate
  around the sun. Comets are made up of frozen ammonia, methane, and small
  amounts of rocky material. Asteroids are made up of rocks, metals, and
  water. 
  Conclution : Scientists and astronomers have been studying our solar
  system for centuries. They are trying to get more information and we hope that
  day by day they'll discover many mysterious things about the solar system.