My name is Mina, and I live in Seoul, where we have four seasons. Each season has its own beauty. In spring, cherry blossoms cover the hills, and in summer the air feels hot and damp. In autumn, the mountains turn red and gold, and in winter, snow may cover the streets.
One evening, I asked my dad why the seasons change. Instead of answering right away, he brought a globe and a desk lamp into the living room. 'Imagine that this lamp is the Sun,' he said. 'The Earth moves around the Sun once a year, and its path is called an orbit.'
Next, Dad pointed to the metal rod that went through the globe. He told me that the rod stands for the Earth's axis, an imaginary line that the Earth spins around. I noticed that the axis was not straight up and down. Instead, it had a slight tilt.
As Dad moved the globe around the lamp, the axis always pointed the same way. In summer, our half of the Earth leans toward the Sun, so sunlight hits the ground more directly and the days are longer. Because of this, the temperature rises. In winter, our half leans away from the Sun, so the sunlight is weaker and the days are shorter.
'So is the Earth closer to the Sun in summer?' I asked. Dad shook his head and said that the distance changes only a little and is not the reason. In fact, when Korea has summer, Australia has winter, because the southern half of the Earth leans away from the Sun at that time.