Why are days and nights equal at all places on earth on September 23? What are the seasons in the Northern and the Southern Hemispheres on this date?

What is meant by Summer Solstice? When do we have Summer Solstice in the Northern Hemisphere?

What will be the duration of daylight on March 21st at 23°30'N and 66°30'S latitudes? Give reason.

Briefly describe the cycle of seasons with the change in inclination of the sun's rays. Which temperature zone receives almost vertical rays of the sun and which zones receive slanting rays?