NCERT Class 6 Geography Chapter 1: Earth in Solar System YouTube Lecture Handout
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NCERT Class 6 Geography Chapter 1: Earth in the Solar System
Galaxy
- Gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter
- Example, Milky Way (contains Solar System)
- March 2016, Most distant galaxy – GN-z11
- Hubble՚s Classification
- Elliptical (E)
- Spiral (S) : Andromeda & Sombrero (unbarred)
- Lenticular
Celestial Bodies (Sun, Moon, Objects in Night Sky)
- Celestial Bodies
- Emit their own heat and Light – Star (Example, SUN)
- Don՚t emit their own light – Planets
- Planets – Greek Word – Planetai i.e.. Wanderer
- NORTH STAR – POLE STAR – Indicates north Direction
Constellations (Group of Stars) – 88 Officially
Planets
Dwarf Planets
- Ceres - largest object in asteroid between Mars and Jupiter
- Pluto – Small Size, Offbeat Orbit, Beyond Kuiper Belt, Now Planetoid
- Eris - 2003 UB313 – 10th planet & largest dwarf discovered
- Oort Cloud are composed of ices like ammonia, methane & water
- Kuiper Belt – Ice belt beyond Neptune
- Planet Nine in Kuiper Belt is 10 times the mass of Earth and 5,000 times the mass of Pluto.
- Kuiper similar to asteroid belt between Mars and Jupiter
Earth
- Shape – Geoid or Oblate Spheroid
- 3rd nearest to sun
- 5th largest planet
- Age: 4.54 billion years old
- Chemical composition of Crust – Silica, alumina, lime
- Earth՚s mass - Iron (32%) , Oxygen (30%) , Silicon (15%)
- Earth՚s Crust – 47% Oxygen
- Rotation & Revolution
- Earth՚s perihelion (closest) around 3 January & aphelion around 4 July.
Moon
- Natural Satellite – Celestial body that moves around planet
- Moon՚s Diameter – 1⟋4th of earth 5th largest natural satellite
- Tides: Gravitational attraction between moon and earth
- Ganymede – Largest moon in Solar System (Jupiter)
- Titan – 2nd largest moon in solar system (Saturn)
- Distance from earth: 384,400 km
- Sidereal Month: w. r. t. to distant stars, 1 revolution relative to stars – 27.32 days
- Synodic Month: w. r. t. to Sun, time taken by moon to reach the same visual phase - 29.53 days. Longer period is required to achieve similar alignment of Earth, the Sun, and the Moon.
- Chandrayaan-I and II, TeamIndus (Unmanned spacecraft to moon)
- Asteroids
- Meteoroids
- Comets
- Pulsars
✍ Manishika