2Day 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.
4SeasonsIf 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.