|Board||CBSE Board, UP board, JAC board, HBSE Board, Bihar Board, PSEB board, RBSE Board, UBSE Board|
|Subject||GEOGRAPHY | Social Science|
|Chapter Name||The Earth in the Solar System|
|Topic||The Earth in the Solar System CBSE Class 6 GEOGRAPHY Chapter 1 Notes|
|Especially Designed Notes for||CBSE, ICSE, IAS, NET, NRA, UPSC, SSC, NDA, All Govt. Exam|
The Earth in the Solar System
- The whole sky is filled with tiny objects, which look like diamonds-some of them are bright, while others are dim.
- When watching carefully, some of them appear twinkling and some appear only glowing like moon.
- Along with these objects, moon is also visible on most of the days.
- It may appear in different shapes, times and positions.
- The full moon appears only once in a month which is called full moon night or Poornima, But after a fortnight (a period between full moon and new moon) one can not see it at all.
- This is the time of “New moon night” or Amavasya.
- On this night one can observes a clear view of sky.
- The brightness of the sunlight doesn’t allow us to observe these bright objects of the sky, which are clearly visible at night.
- The objects we see in the sky like the sun, the moon, stars are called celestial bodies
- The stars are celestial bodies having a large size, heat, and light-emitting nature and are made up of gases, For example, the sun.
- These stars appear as very small particles at night though they are similar to the sun, we can’t feel their heat or light because they are far away from the earth.
- While watching the night sky, one may notice different groups of stars arranged in various patterns which are called constellations.
- Ursa Major or Big Bear is an example of one such constellation.
- The constellation that is very common and could be easily seen is Saptarishi (sapta-seven, rishi-sagers), or small bear-a group of seven stars, that forms a part of the large Ursa Major Constellation.
- The ancient people used to determine directions with the help of stars during the night.
- The Pole Star or North star always remains constant and shows the North direction.
- One can locate the position of the Pole star with the help of the Saptarishi.
- For example, if an imaginary line is drawn joining the pointer stars and extended further, it will point to the Pole star.
- Planets are those celestial bodies which are lit by the light of the stars and do not possess light emitting character, e.g. the Earth, the Jupiter, the Venus etc.
- The earth gets all its light and heat from the sun, which is our nearest star.
- The other planets in our solar system also get heat and light from the sun.
- If we go far from the earth, it will appear to be shining just as the moon.
- A satellite is an object that moves around planets.
- The moon is a satellite of the earth.
- Some of the other planets also have their moons.
- Some planets have rings at their outer surface, such as Jupiter, Saturn and Uranus.
- These rings are made up of belts of debris which can be seen from the earth too by using powerful telescope.
The Solar System
- The solar system or solar family comprises of the sun, eight planets, satellites, other celestial bodies like asteroids, meteoroids etc with the sun at the centre of it.
- The sun is the head of the solar system and a massive body made up of extremely hot gases.
- The pulling force of the sun binds the entire solar system.
- The ultimate source of heat and light in the solar system is the sun.
- Though we can’t feel its immense heat because of its far distance from the earth.
- The word ‘planet derives from the Greek word “Planeta” meaning wanderers’ or ‘moving.
- There are eight planets in our solar system which move in a fixed path around the sun. These elongated paths are called orbits.
- According to the distance from the sun, the planets can be arranged as: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
- Mercury is the nearest planet (takes only 88 days to complete one round alongits orbit) and Neptune is the farthest planet from the sun.
- Venus because of its shape and size is similar to the earth is considered as “Earth’s-twin”.
- Pluto is regarded as dwarf planets like-Ceres, 2003 UB 313, after the meeting of International Astronomical Union in August 2006.
The earth is the fifth largest planet in size while the third nearest planet to the sun. The shape of the earth is called Geoid (meaning Earth like shape) because of its slightly flattened shape at poles.
The existence of life on earth makes it unique in solar system.
The life on earth has been possible due to following favourable conditions:
- Presence of air with life supporting gases like oxygen.
- Neither extremely hot nor extremely cold.
- Presence of water.
- The earth is known as blue planet due to the presence of water on two-third part of its surface, that makes it look blue from the outer space.
The Moon as a Satellite
- A satellite is a celestial body that moves around the planets as the planet moves around the sun. It may be natural or man-made.
- The moon is the only satellite of the earth.
- It has no life due to absence of life-supporting conditions.
- The surface of the moon is covered with plains, mountains and depressions which is observable as shadows on full moon day.
- The moon is 384400 km away from the earth. The diameter of moon is only a quarter of the earth.
- It looks big due to its closeness to the earth than other celestial bodies.
- The moon moves around the earth in about 27 days. It takes exactly the same time to complete one spin (round) of earth.
- This makes only one side of the moon visible from the earth.
- Apart from the stars, planets and satellites, there are small celestial bodies in numerous amounts between the orbits of Mars and Jupiter that move around the sun called asteroids.
- Scientists believe that these are the parts of a planet, which are formed by the explosion of that planet many years ago.
- The small pieces of rocks which move around the sun are called meteoroids.
- Sometimes, these objects come close to the earth and drop upon it.
- While dropping on the earth, they get heated up and burn due to friction with the air and appear as flash of light.
- Meteors sometimes do not get burn completely and strike the earth surface creating a hollow.
- An artificial satellite is a man-made object that is designed to gather information about the universe or for communication.
- It is placed in orbit around the Earth and carried through a rocket from Earth’s surface. India has lots of satellites in space, some of them are INSAT, EDUSAT, IRS, etc.
Universe and Galaxy
- The universe comprises of millions of galaxies.
- We all are part of the universe.
- It is very difficult to find out the size of the universe because of its huge expansion.
- A galaxy is a huge system that contains billions of stars, gases and clouds of dust.
- Our solar system is a part of Milky Way Galaxy.
- This galaxy is a cluster of millions of stars that appear as a glowing path across the sky on a clear night It was named Akash Ganga on the basis of imagination done in ancient India that it is a ‘river of light flowing’ in the sky.
One Word meaning
- Celestial Bodies: The objects that remain in space like the sun, the moon, stars etc.
- Constellations: A pattern formed by different groups of star. e.g. Ursa Major, Big Bear, Saptarishi (Small bear).
- Solar System: The sun, planets, satellites and celestial bodies like asteroids and meteoroids make the solar system.
- Satellite: A celestial body that moves around the planet. It may be man-made or natural.
- Asteroids: Tiny bodies that move around the sun and present between orbits of Mars and Jupiter.
- Meteoroids: Small pieces of rocks which move around the sun.
- Orbit: The path in which a planet or satellites move around.
- Geoid: The Earth like shape.
- Universe: Millions of galaxies.
- Galaxy: A huge system that comprises of billions of stars, clouds of dust and gases.