Earth Structure
Geography · पृथ्वी की संरचना · 17 facts
Earth's age is approximately 4.54 billion years. It is the densest planet in the solar system.
Asthenosphere = Semi-molten, plastic-like layer below lithosphere (100–700 km). Plates float on it.
Convection currents in the asthenosphere cause tectonic plate movement.
Earth's shape = Geoid (oblate spheroid)
3 layers: Crust → Mantle → Core
Crust = thinnest, Core = hottest
Continental crust = SiAl (thick, light), Oceanic crust = SiMa (thin, dense)
Mantle = largest layer by volume
Core = NiFe (Nickel + Iron)
Moho = Crust/Mantle, Gutenberg = Mantle/Core, Lehmann = Outer/Inner Core
Lithosphere = Crust + upper Mantle
Asthenosphere = where tectonic plates float
Rotation = day/night (24 hrs), Revolution = seasons/year (365.25 days)
Equator = 0° Latitude, Prime Meridian = 0° Longitude
Tropic of Cancer = 23.5° N, passes through 8 Indian states
IDL = ~180° Longitude, crossing changes date
IST = GMT + 5:30, based on 82.5° E (Mirzapur)