These DAV Class 6 SST Notes and DAV Class 6 SST Chapter 1 Notes – The Planet Earth and the Solar System hold significant importance as study material for students.
The Planet Earth and the Solar System Class 6 DAV Notes
→ All the objects in the sky which appear similar to us, are the heavenly or celestial bodies. For example, the sun, the stars, the moon, the planets, etc.
→ These celestial bodies spread over the vast space which is also called universe.
→ The distribution of the billions of celestial bodies in the space is not uniform. The countless stars in the space form huge clusters. These stars are held together by mutual gravitational force. Galaxy and Milky Way (Akash Ganga) are made up of billions of stars.
→ Stars are self-luminous heavenly bodies. They generate heat and light and radiate it in the space. They look very small as they are very far away from the earth.
→ Stars in the clear sky appear to form different shapes and patterns and move from west to east. Constellations are actually groups of stars, e.g., Big Bear or the Great Bear. There are several other formations of stars, which have been given name by the astronomers.
→ The sun and its companion celestial bodies constitute the solar system. The eight planets, their companion satellites, asteroids, meteors and comets are the members of the solar system. They all revolve around the sun in their fixed paths called orbits.
→ The sun is the head of the solar system. It generates heat and light and radiates them into the space. All the members of the solar system receive heat and light from the sun. The sun is the nearest star to the earth as compared to other stars.
→ Planets are the heavenly bodies which receive light and heat from the sun. There are altogether eight planets. In order of their distance from the sun, they are- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
→ The first four planets are made up of solid material like rocks and the next four are the gaseous bodies.
→ There is a great variation in time taken by each planet to complete one rotation on its axis as well as one revolution around the sun.
→ The earth, on which we live, is a unique planet. It contains favourable environmental conditions for the origin and survival of all forms of life. No other planet is suitable for life.
→ Satellites also do not have their own light and heat. They reflect light which they receive from the sun. Each planet has one or more satellites, except the Mercury and the Venus. Our earth has one satellite, called the moon.
→ The moon is the closest celestial body to the earth. It also reflects light which it receives from the sun. It rotates on its axis and also revolves around the earth.
→ The moon does not have atmosphere around it. It becomes very hot during the day time in the light of the sun and very cold during night or in shadow.
→ The position of the moon in rotation to the sun changes every day. When the illuminated side of the moon is fully hidden from our view, it is called the New Moon. The day when the moon is completely visible to us, is the full moon day. After this day, the decline of the moon’s illuminated part starts. The illuminated part slowly disappears and the moon again comes to the position of new moon.
→ Other celestial bodies that revolve around the sun are asteroids, meteors and comets.
→ Universe:The vast limitless space which includes all celestial bodies.
→ Galaxy: A huge cluster of billions of stars, that form a particular shape.
→ Milky Way: A strip of faint white light stretching across the sky from north to south.
→ Stars: Self-luminous heavenly bodies generating heat and light.
→ Light year:A unit to measure the distance between celestial bodies.
→ Constellation: The group of stars which are recognised by their formations.
→ Nebula: A giant cloud of gases and dust.
→ Solar system: The sun and its companion celestial bodies constitute the solar system.
→ Sun: A very huge mass which generates heat and light and radiate them into the space.
→ Moon: The closest celestial body to the earth.
→ New Moon: When the illuminated side of the moon is fully hidden from our view, it is called the new moon.
→ Planet: A heavenly body which receives light and heat from the Sun.
→ Satellite: A heavenly body that revolves around its respective planet.
→ Asteroid: A planetary body which revolves around the sun.
→ Meteor: A very small planetary mars which often enters earth’s atmosphere and gets burnt due to friction.
→ Comet: A small body with a head and long luminous tail.
→ Astronomers : Scientists who study celestial bodies.
→ Cluster : A group of the similar elements gathered closely in a bunch.
→ Crescent shape : A single curve that is broad in the centre and tapers to a point at each end.
→ Furnace : An enclosed chamber in which material can be heated at very high temperatures.
→ Gravitational force : A force that attracts any object with mass.
→ Self-luminous : Objects having property of emitting light.
→ Spherical : A shape slightly flattened at the top.