Chapter Notes and Summary
• Sun, moon all those objects shining in sky are called celestial bodies.
• Celestial bodies which have their own heat and light are called Stars.
• Sun is a Star.
• Various patterns formed by different groups of stars are called constellations e.g. Ursa Major or Big Bear.
• Small Bear or Saptarishi is a group of seven stars.
• North Star indicates North direction. It is also called Pole Star.
• We can locate position of Pole Star with help of Saptarishi.
• Some Celestial bodies which do not have their own heat and light and glow by light of stars are called planets.
• moon that we see in sky is a satellite.
• Solar system l sun, nine planets satellites, asteroids and meteoroids form solar system.
• Sun l sun is in center of solar system.
• It is made up of extremely hot gases.
• sun is about 150 million km away from earth.
• Planets l There are nine planets in our solar system.
• nine planets are Mercury, Venus, Earth, Mars, Jupiter, Uranus, Neptune and Pluto.
• Planets move around sun in a fixed orbit.
• Mercury is nearest planet.
• Pluto is farthest planet.
• A new planet 2003 UB313 has been discovered. It is bigger than Pluto and is farthest from sun.
• Earth l It is third nearest to sun and fifth largest planet of our solar system.
• earth is a unique planet because it supports life.
• It is also called blue planet.
• It’s shape is Geoid.
• Moon l It is only satellite of earth.
• Its diameter is one-quarter of earth.
• It is about 3.84,400 km. away from us.
• It moves around earth in about 27 days.
• Only one side of moon is visible to us on earth.
• No life exists on moon as it has neither water nor air.
• Asteroids l They are numerous tiny bodies which move around sun between orbits of Mars and Jupiter.
• largest asteroid is Ceres.
• Meteoroids l small pieces of rocks which move around sun are called meteoroids.
• Our solar system is a part of Milky Way galaxy.
• Milky Way galaxy was named Akash Ganga.
• There are millions of galaxies that make Universe.