Earth

1. Eratosthenes first measured the Earth's radius. 
2. Earth rotates around its own Axis.
3. The gravity of Moon as compared to Earth is 1/6. 
4. The most important layer of earth is The mantle.
5.  Distance from Earth is the GEO (Geostationary orbit) located 4000 Km. 

1. Geophysics is the branch of Earth science that applies the principles and methods of physics to study the physical properties, structure, composition, and dynamic processes of the Earth, including its interior, surface, oceans, and atmosphere.
2.  Meteorology is the branch of Earth science that deals with the study of the atmosphere, particularly weather processes and phenomena, using the principles of physics and mathematics. 
3. Plasma physics deals with the study of ionized gases (plasma) in which free electrons and ions interact and are strongly influenced by electric and magnetic fields.                                                                                                                                       Memory tip:
   Plasma = Ionized gas + EM fields
4. Hydrology is the branch of Earth science that deals with the study of water, its occurrence, distribution, movement, and properties on, below, and above the Earth’s surface.  Hydrology = Water on Earth . 

1.  Meteorology is the branch of Earth science that deals with the study of the atmosphere, particularly weather processes and phenomena, using the principles of physics and mathematics. 
2. Geology is the branch of Earth science that deals with the study of the Earth, including its origin, structure, composition, rocks, minerals, and the processes that shape it.  Geo = Earth + Logy = Study 
3. Oceanography is the branch of Earth science that deals with the scientific study of oceans, including their physical, chemical, biological, and geological aspects.  Oceanography = Oceans 
4. Astronomy —
   • Astronomy is the branch of science that studies celestial bodies.
   • It deals with stars, planets, moons, comets, asteroids, and galaxies.
   • Studies the origin, evolution, and motion of heavenly bodies.
   • Uses telescopes and satellites for observation.
   • Helps in understanding the universe beyond Earth.

Memory tip:
Litho = rock

1. Quick exam tips:
   • Crust = rocky part 
   • Lithosphere = rigid crust + upper mantle 
   • Asthenosphere = soft/ductile mantle 
   • Core = magnetic field + heat source