Why Day, night, seasons and Gravity happen

Day and night happens because the Earth rotates. So at any time, half of the Earth is facing the Sun, so it is bright and day time there and the other half is facing away from the Sun so it is dark and night time. As the Earth continues to rotate, parts that were facing the Sun are soon facing away from it and the parts facing away from it are now facing it, so everywhere gets day and night.

The earth spins on its axis and it takes 24 hours to complete one full rotation. The earth has a northern hemisphere and a southern hemisphere with the equator round the middle. The earth spins at an angle of 23.5 degrees and it is this which causes the seasons. When the northern hemisphere is tilted away from the sun this is winter because the sun's rays are more less spread out and the sun is lower in the sky. At the same time when the southern hemisphere is tilted towards the sun the sun's rays are more spread out and the sun is higher in the sky - this would be summer.

Gravity is a force that pulls you to it earth has enough gravity to keep us on the ground and not 0 gravity or we would just float in the air and end up being space or not too much or the people on earth be dwarfs.