Ch1-Earth as a planet

• Earth as a Planet: Shape of the earth. Earth as the home of humankind and the conditions that exist.
• Earth, our home planet, is the third planet from the sun and the fifth-largest planet in the solar system. It is the only planet which supports life.
• From space, the earth looks blue because 70 per cent of its total area is covered by water. Hence, it is also called the watery planet.
• Members of the solar system

  • Planets
  • Satellites that revolve around the planets
  • Asteroids
  • Comets
  • Meteorites
• Planets in order of their distance from the sun

  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
• The shape of the earth

  • It bulges slightly at the centre and is flattened at the poles
• Aryabhatta


  5th century Indian astronomer and mathematician who believed the earth was spherical in shape and rotated on its axis
• Pythagoras


  6th century Greek philosopher who said the earth was spherical in shape
• Proof that the Earth is Spherical in shape

  1. Sighting of a ship

  2. Bedford Level Experiment

  3. Pole Star

  4. Satellite Pictures

  5. Lunar Eclipse

  6. Circular Horizon

  7. Sunrise and Sunset

  8. Circumnavigation
• The earth is not a perfect sphere. It bulges slightly at the centre and is flattened at the poles.
• Oblate Spheroid


  The shape of the earth, which is slightly flattened at the poles and bulges at the equator
• The earth is the only planet that supports life.
• Features that make the Earth habitable


  • Distance from the Sun
  • Temperature
  • Atmosphere
  • Water
  • Solid Crust (Lithosphere)
  • Biosphere
• Biosphere


  The narrow realm of contact and interaction between the atmosphere, lithosphere and hydrosphere
• Biosphere provides all the necessities for all the species living on earth, i.e., light, heat, water, food and habitats.
• Within the biosphere, life is found chiefly in two forms-the plant kingdom and the animal kingdom.
• The Earth has an average temperature that supports liquid water and enables photosynthesis by plants.
• The Earth's atmosphere protects us from solar radiation, provides oxygen to breathe, and allows water to exist on its surface.
• The Earth's magnetic field protects it from solar winds and cosmic rays.
• The Earth's crust is solid and allows for the formation of landforms such as mountains and valleys.
• The Earth's crust consists of solid rock and provides stability and support for life.
• The Earth's atmosphere contains oxygen produced through photosynthesis by plants.
• The Earth's oceans cover over 70% of its surface area and are essential for regulating climate and supporting marine ecosystems.
• The Earth's climate is influenced by factors such as greenhouse gases, ocean currents, and atmospheric circulation patterns.
• The Earth's geosphere consists of rocks, minerals, and soil, providing resources for construction and agriculture.
• The Earth's atmosphere regulates temperatures and prevents extreme fluctuations.
• The Earth's atmosphere filters out most ultraviolet light from the sun.
• Flat Earth


  • If the earth were flat, the entire ship would have been visible at once
• Spherical Earth


  • The earth's surface is curved
  • The ship comes into full view
• Bedford Level Experiment


  1. Three poles of equal length fixed at intervals of 5 km

  2. Poles had the same height above the water in the canal

  3. Viewed from one end of the canal
• When the poles were viewed from one end of the canal, the