Solar System

Hi readers, we are starting with a very interesting topic – Solar System. So strap yourself in and take a tour to the exciting world of our solar system . 🙂 


The topic we are revising today comes under “cosmology”, the branch of astronomy. This word is a combination of cosmos (universe) + logos (science), which makes “study of the universe” as a whole.


  • Our solar system is comprised of sun, 8 plants and countless other smaller heavenly bodies viz. asteriods, meteors, comets and satellites of the planets, dust and gas. Everything in the solar system revolves around the sun in elliptical order.
  • The Sun is at the center of the solar system and all the bodies are revolving around it due its gravitational pull. The astronomical model of planets revolving around the sun is called as Heliocentrism.


Theory Behind the Origin of Universe


  • The Big Bang Theory explains the origin of the universe. As per theory, an explosion was occurred 15 billion years ago, which headed towards the formation of galaxies and other heavenly bodies. It is believed that before big bang, the matters of the universe were a concreted lump called primeval atom.


Scientists Behind the Discovery of Solar System

  • Aristarchus – He had theorized on a heliocentric reordering of the universe. (Ancient idea)
  • Nicolaus Copernicus – He was the first to build up a mathematical system that depicted “solar system”.
  • Galileo Galilei – He was the first to discover physical details about the individual bodies of the Solar System.
  • Isaac Newton – He brought the laws of physics to the solar system.
  • Edmond Halley – He realized that comets are part of the solar system.


Belts of Solar System

  • Asteroid Belt – It is located in an area between the orbits of Mars and Jupiter. The four largest asteroids in the belt are Ceres, Vesta, Pallas, and Hygiea. The asteroid belt is also termed the main asteroid belt or main belt.
  • Kuiper Belt – It extends beyond the planet Neptune (outer solar system). The largest Kuiper Belt Objects are Pluto, Quaoar, Makemake, Haumea, Ixion, and Varuna. These are often also referred to as Trans-Neptunian Objects (TNOs). It contains bodies made mostly of ices. It is also referred to as Kuiper-Edgeworth Belt.
  • The Oort Cloud – It is not really a cloud. It is a mass of a trillion of comets which extend far beyond the planets of the Solar System. The Oort Cloud extends 13,950,000,000,000 miles from the Sun. The Oort orbits are not planar like the Asteroid and Kuiper belts.


Members of Solar System


Solar System sun
Different regions of sun

Solar System Parts of sun

  • Core – Centre of the sun where energy is produced by nuclear fusion. It is the hottest part of the sun.
  • Radiation zone – The core is surrounded by the radiative zone. It is the region where energy is transported by radiation flow.
  • Convective Zone – Radiative zone is enclosed within the convective zone. It is the region where energy is transported by convection cells.
  • Photosphere – The innermost part and shinning part of the sun’s atmosphere, the only part we can see. It is the surface where photons are emitted.
  • Chromosphere – It is the atmosphere of the Sun.
  • Corona – It is the extremely hot outermost layer. It is the region where solar wind originates. Corona is visible during a total eclipse or solar telescope called Coronagraph.


About Sun spots, Solar flares and Solar winds:

  • Sun Spots – The slightly cooler areas of the sun are known as sunspots as they appear darker in color. They generally increase in intensity and then decrease over a period of 11 years. This 11 year cycle is known as the Saros Cycle.
  • Solar flares – During high solar activity, the Sun releases massive amounts of gas and plasma into its atmosphere which are known as solar flares. They interact with Earth’s magnetic field to create beautiful light shows known as the Northern and Southern lights aka Aurora Borealis. It can cause radio interference via the ionosphere.
  • Solar Winds – As the Sun burns hydrogen at its core, it releases vast amounts of atomic particles into outer space. These atomic particles along with the sun’s radiation create a sort of wind, known as the solar wind. It can disrupt satellite communications and knock out power on Earth.



Readers, keep in mind that the planets of our solar system are divided into Inner planets and Outer planets. The difference is shown as below:

Solar System Planets

  • Planets visible to the naked eyes – Mercury, Venus, Mars, Jupiter and Saturn.
  • Dwarf Planets – There are 5 dwarf planets which include Ceres, Makemake, Haumea, Eris and Pluto.
  • Nearest Planet – Mercury
  • Farthest Planet – Neptune


Here comes the important facts about various planets and satellite

MERCURY – The Smallest Planet

Let’s start with the younger and faster one of our solar system, which was named after the Roman messenger God Mercury, the fastest Roman god. As it is the closest planet to the sun, so obvious it would be extremely hot, therefore it has no water and life building gases on it. Our baby planet is so little, that, more than 18 mercurys needed to make it equivalent to earth.


  • Other Charaterstics:

 Solar System Mercury


VENUS – Bright Queen of sky

Here comes the beauty, “Venus”, which was named after the Roman Goddess of love and beauty. Venus appears in the eastern sky before sunrise. Sometimes, it appears in the western sky just after sunset. That’s why it is called as “morning and evening star”. It is also known as “earth’s twin”because of its same size and mass as of earth.


As it is beautiful, so by default it would be “hot” :p. It is the hottest planet due to its veil of cloud. But due to its brightness, Venus became so egoistic that it started rotating in a clockwise direction (unlike other planets). It spins backward. This means that the sun rises in the west and sets in the east on Venus.


  • Do you know why Venus is bright?

It is the brightest planet because of albedo. Albedo is the proportion of radiation reflected by the surface. It is high in snow or white color and in low in black color (absorption).


  • Other Charaterstics:

Solar System Venus


EARTH – The Goldiloack Zone

Let’s introduce our home to the whole universe. Our home looks like “blue marble” from space, which makes it so lovable, that, we call it as “watery planet“, because water covers 71% of the earth’s surface and also “Goldilock Planet” as it fulfill all conditions for a sustainable life. It’s uniqueness doesn’t stop here, it is also the only inner planet with large satellite (moon).


  • Do you know our home has many unique features like:

It is also the only inner planet with large satellite (moon). It protects us from harmful ultraviolet radiations of the sun from a protective planet called “ozone layer”. The axis of rotation of the Earth is not perpendicular to the plane of its orbit. The tilt is responsible for the change of seasons on the Earth.


  • Other Charaterstics:



MARS – The Red planet

Now, the turn of 4th planet, which was named after the ancient Roman God of War due to its resemblance with the color of blood. Greeks dubbed its name as “Ares”while Egyptians called it as “Her Desher”.  It is a very cold planet and like the earth, it has North and South polar ice caps. Scientists have found ancient flood evidences on Mars and also of water in the form of icy soils and thin clouds.

  • Do you know, why it is called as the red planet?

Iron minerals in the Martian soil oxidize or rust causes the soil and the dusty atmosphere  to look red.

  • Other Characteristics:


     – Indian MissionMars Orbiter Mission (MOM)


JUPITER – The Biggest Planet

Here comes the Big P, which was named after the king of Roman Gods. It is the second brightest planet after Venus. It is a giant gas planet covered with dense red, brown, yellow and white clouds. Due to its windy weather, it has famous “Great Red Spot” which looks like a hurricane. It also has the strongest magnetic field.


  • Other Charaterstics:

– Its largest four are called Lo, Europa, Ganymede, and Callisto. These four moons are called the Galilean satellites because they were first seen in 1610 by the astronomer Galileo Galilei.


SATURN – The Ringed planet

Followed by Jupiter in queue and also in size, the “Jewel of solar system” was named after Roman God of farming. It is the only planet that could float in water :p i.e. “lightest planet”. It’s bright concentric rings are made up of ice, dust and rock.


  • Other Charaterstics:

– Titan is the only satellite with an atmosphere like Earth.


URANUS – A planet on its side

The extremely cold planet was named after the Greek God of the heavens. It is the first planet discovered by the use of a telescope by Sir William Hersiel. It appears greenish in color due to the presence of methane gas in its atmosphere. Like Venus, it also has a retrograde rotation (east to west). It has the largest tilt and spins on its side. It is the only planet whose equator is nearly at right angles to its orbit.


  • Other Charaterstics:


–  It has 5 major moons – Miranda, Ariel, Umbriel, Titania and Oberon.


NEPTUNE – Sister ice giant to Uranus

Here comes the terminator, the twin of Uranus, which was named after the Roman God of Sea. It is a great ball hydrogen and helium. It is surrounded by methane rings of sub zero temperature. Urbain Le Verrier predicted the existence of Neptune before it was actually observed.


  • Other Charaterstics:


Its largest moon is Triton, is the only large moon in the Solar System with a retrograde orbit, an orbit in the opposite direction to its planet’s rotation.


Now, go back to childhood and remember My Very Educated Mother Just Showed Us Neptune”. It’s the trick to remember the sequence of planets.


  • Pluto is not in the list of our classical planets. After its cancellation of membership, it was assigned with an asteroid number 134340 reflecting its new status as dwarf planet.
  • Its satellites Charon (Pluto’s largest moon), Nix and Hydra are now called as 134340 I, II and III.


Other bodies of Solar Sytem



Now, we will revise Selenology (study of the moon). The moon revolves around the earth in an elliptical orbit. Its light is actually the light of the sun, which is reflected by the moon’s surface. It’s brightest parts are abounded with mountains, of which, Liebuity mountain is the highest mountain with a height of 10,660 meters whereas its dark patches are low lying plain. When a month has two full moons, the second full moon is called a blue moon.


  • Other Charaterstics:




Asteroids are solid, rocky and irregular bodies, which orbit our sun, mainly in a region of space between the orbits of Mars and Jupiter known as the Asteroid Belt. Asteroids that pass close to the earth are called Near Earth Objects (NEOs) or Potentially Hazardous Asteroids (PHAs).  Presently, there are 670,452 asteroids.


  • Other Charaterstics:




Comets are the fragments of frozen gases, ice and rock. The term comet derived from the Latin word “Stella cometa” meaning “hairy star” that appeared in the sky unannounced and unpredictably. They are also known “dirty snowballs“. Its striking feature is its long luminous tail, which emits light. Presently, there are 3,319 comets.


  • Other Charaterstics:




Meteors are fragments of rocks which are formed due to the collision of asteroids with one another. It is a streak of light (shooting stars) that appears in the sky when a particle from asteroid and comet enters the Earth’s atmosphere. They are usually burnt up before they reach the earth’s surface due to the heat produced by air resistance, but if they do not burnt up completely, they land on the earth’s surface and are known as meteorites.


  • Other Charaterstics:




A star is a huge ball of hot, glowing gas, mostly hydrogen and helium. They produce their own light and energy by a process called nuclear fusion. There are 1022 stars in the universe. The stars appear to move from east to west because the earth rotates from west to east on its axis.STARS


  • After Sun, Proxima Centauri is the closest star to the earth. It is 4.24 light years away.
  • The coolest stars appear red, while the hottest stars are blue.


Do you know why stars twinkle?

The scientific name for the twinkling of stars is stellar scintillation. The twinkling of stars is due to atmospheric refraction of starlight. As a star’s light enters our atmosphere, each single stream of it is refracted, which result in a slight change of direction by the temperature and density layers in Earth’s atmosphere. To our eyes, this makes the star seem to twinkle.



A group of stars that forms a particular shape in the sky is called as a constellation. There are small patterns of stars within a constellation are called asterisms. Presently, there are 88 constellations.


– With the help of Ursa Major (Saptarishis), we can locate a pole star or North Star.


  • Other Charaterstics:




A galaxy is a group of stars, gas, dust and black holes. There are 1011 galaxies in the universe.


  • Other Charaterstics:



LAST but not the LEAST


  • Zinnia: The first ever flower grown in space

In January, 2016, Zinnia became the first flowering plant grown outside Earth’s atmosphere. The flowers appear similar to those grown on Earth, except for the curled edges of the petals, which could be due to the zero-gravity conditions. The system uses red, blue and green LED lights to simulate sunlight.


Hope you have learned today


Click for the Quiz of the topic 


Please give your feedback, we are ready to serve better  🙂 

Subscribe and Share ! 

Keep Visiting !

Happy Learning !