Nature of Physical World and Measurement
Laws of Motion
Work, Energy and Power
Motion of System of Particles and Rigid Bodies
Properties of Matter
Heat and Thermodynamics
Kinetic Theory of Gases
- Heliocentric system over geocentric system
- Kepler’s Third Law and The Astronomical Distance
- Measurement of radius of the Earth
- Interesting Astronomical Facts
- Recent developments of astronomy and gravitation
Explain how geocentric theory is replaced by heliocentric theory using the idea of retrograde motion of planets.
The following photographs are taken from the recent lunar eclipse which occurred on January 31, 2018. Is it possible to prove that Earth is a sphere from these photographs?
A student was asked a question ‘why are there summer and winter for us? He replied as ‘since Earth is orbiting in an elliptical orbit, when the Earth is very far away from the Sun (aphelion) there will be winter, when the Earth is nearer to the Sun (perihelion) there will be winter’. Is this answer correct? If not, what is the correct explanation for the occurrence of summer and winter?