Each year brings four seasons — spring, summer, autumn and winter. In summer the weather is warm and the days are long; in winter it is cold and the days are short. Many people assume this happens because the Earth moves closer to the Sun in summer, but that idea is simply wrong.
The true cause is the tilt of the Earth. Our planet does not sit upright as it orbits the Sun; instead, it leans over at an angle. As the Earth travels around the Sun over the course of a year, this tilt stays pointing in the same direction in space.
Because of the tilt, there are times when the top half of the Earth leans towards the Sun. Then sunlight strikes it more directly, the days grow longer, and that half enjoys summer. At the same moment, the bottom half leans away, receives weaker, more slanted light, and experiences winter. Six months later the situation is reversed. This is why the two halves of the world always have opposite seasons: when it is summer in Europe, it is winter in Australia.
