Earth’s Rotation and Revolution
What time of day do you feel the most heat outside? Is it hottest during the middle of the night, during the morning, or during the afternoon? The Sun produces so much heat, that it only takes a few hours for it to raise the temperature of the Earth’s surface by several degrees. After rising in the east on a cool morning, the energy from our Sun begins to shine down on us, warming everything around us. As the day progresses, it gets warmer and warmer. After setting in the west, our atmosphere begins cooling down very quickly. What would happen if the Sun didn’t rise one day? How long would it take for everything around you to freeze? Within a few days it would be very cold indeed.
What causes the Sun, moon, and stars to rise in the east, and then later set in the west each day? Imagine that you are standing in your backyard on a small merry-go-round. As your friends push you faster and faster, it appears to you as though the world is spinning in circles. First you see your house, then the fence, then the other fence, then your house again, then the fence again, and so on. Is your backyard really spinning out of control? Of course not. It only looks that way because you are spinning.
In a way, the Earth is like a giant merry-go-round. Instead of giant friends pushing the Earth in circles, the Earth’s spin, or rotation, was caused by forces during its creation. The Earth was formed amidst a giant cloud of dust and gas. Slowly, over many millions of years, this dust and gas slowly condensed under the force of its own gravity, forming a small mass. As the mass grew larger and larger, so did the force of its gravity. As the young Earth’s gravity became more powerful, it began attracting dust and gas towards it at a faster rate. This caused a sort of traffic jam, as these materials raced towards the Earth. What resulted was a giant whirlpool-like swirl of dust and gas. Consider what happens when you drain your bathtub. As the water all tries to rush down the drain at the same time, a circular funne, l or whirlpool, is created.
Eventually as the young Sun became hotter and brighter, the remaining gas and dust found in the Solar System were blown away. The Sun’s powerful stellar winds cleaned out the Solar System, meaning that the Earth could not grow any larger. Even though the swirling cloud of dust and gas are long gone, the Earth continues to rotate to this day, and will continue rotating throughout its entire planetary life.