Diamond ring in Solar eclipse

An eclipse is a natural phenomenon. A solar eclipse is a type of eclipse that occurs when the Moon comes between the Sun and the Earth (at the stage of New Moon). At this stage the Moon fully or partially blocks the Sun. In total solar eclipse, the Sun is fully covered by the Moon and in partial and annular solar eclipse, the Sun is partially covered by the Moon.

In every month, the Moon comes between the Sun and the Earth.

But why does the solar eclipse not happen in every month? Because the Moon, the earth and the Sun always must be in same orbital plane and also in same straight line to get this event happened. Moon's orbit is inclined at more than 5 degrees to the Earth's orbit. So the shadow of the Moon at the New Moon misses the Earth. The distance between the Earth and the Moon also has also a major part in it. Because if the Moon can't cover the Sun perfectly (as we see from the Earth), the phenomenon can't be seen. The total solar eclipse is rare because it takes years and years to match the conditions perfectly. 

Now, Why do we see the DIAMOND RING? What is the physics behind it? 

According to Albert Einstein's General Theory of Relativity, the light should not travel in the perfect straight line. While travelling through spacetime (4th dimension) and induced by the matter's gravitational attraction, light should curve towards the G-field. So at the time of the total solar eclipse, the light coming out from the Sun bends due to the gravitational force of the Moon. So the Diamond Ring can be seen.

In May 29, 1919, there was a total solar eclipse and Sir Arthur Eddington performed the first experimental test of Albert Einstein's General Theory of Relativity. The results of this experiment made Albert Einstein world famous overnight.