The Moon moves around the Earth and Earth moves around the Sun. Our whole Solar System moves to bring changes like day and night and change in seasons.
Day and Night
The Earth spins around in axis and completes one rotation in 24 hours. As it spins, some places face the sun and get light. These places have a day. The places not facing the sun have night. As the earth is spinning continuously, the change from day to night and back again goes on. The Earth spins towards the east. So, the Sun seems to rise in the east, and set in the west. Sun doesn’t move across the sky, Earth moves. The sun seems to move because we look at it from the perspective of Earth. Shadow lengths change during the day; the shortest length is during mid-day.
Change in Seasons
The earth orbits around the Sun. It takes 365 days and nights to make a complete orbit around the Sun. While orbiting around the Sun, the earth tilts slightly to one side by 23.5 degrees. The north end of the axis always points towards North Star as the earth circles the Sun. The tilted axis and yearly orbiting causes the variation in the amount of heat at different locations on the Earth causing seasonal changes.
Twice in the year, the sun is furthest from the equator. This refers to “Solstice”.
- The summer solstice is when the sun is the furthest north from the equator. This happens about June 21. So, there is summer in the Northern Hemisphere and most hours of daylight. Southern Hemisphere have winters.
- The winter solstice is when the sun is the furthest south from the equator. This happens about December 22. So, there is summer in Southern Hemisphere and winter in Northern Hemisphere.
The in-between seasons are autumns and spring. There are two times in the year when day and night are of equal lengths, all over the world. This is called EQUINOXES.
Key Facts
- The Earth spins around once every 24 hours.
- The Earth takes one year to orbit the Sun.
- The Moon takes one month to orbit the Earth.
- The Sun lights up half the Earth.
- The seasons occurs because the Earth is tilted.