2 Day and NightThe Earth is a sphere (actually, it’s an oblate spheroid – a very slight rugby ball shape)The Earth orbits the Sun in a path that is egg-shaped – an ellipse. It takes 3651/4 days to orbit the Earth – every 4 years we have an extra day – a leap year.The Earth rotates once in 24 hours. The side of the Earth facing the Sun experiences daylight; facing away from the Sun it is night.
4 SeasonsIf the Earth’s axis was exactly at 90o to the plane of the orbit round the Sun, day and night would last the same time all year round – 12 hours.However, the axis is tilted so we have seasons.If the axis is tilted towards the Sun, day lasts longer – it is Summer.If the axis is tilted away, day is shorter – it is winter.In spring and autumn, the axis is neither towards nor away from the Sun. This is when day and night are the same length; the spring (vernal) and autumn (autumnal) equinoxes.