The Turn of the Earth

The Earth's elegant 24-hour rotation period is one of the characteristics that make life exist on our planet, allowing most of the Earth's regions to be kept at a pleasant and comfortable temperature, bathed in sunlight during the day and darkness at night.

Each planet in the solar system has its own rotation speed. The tiny Mercury, burning very close to the Sun, takes 59 terrestrial days to turn only once. Venus, the second planet, spins once every 243 Earth days. In fact, Venus rotates backwards from the direction of its orbit around the Sun, as does Uranus and the tiny dwarf planet Pluto. Uranus even goes to bed during its working day, turning with its axis of rotation pointing almost directly at the Sun.

source picture: pixabay

Why do the Earth and the other planets rotate? To answer this question, it will be helpful for us to understand how our Solar System was formed. Almost five billion years ago, our Solar System had its beginnings as a vast cloud of dust and gas. The cloud began to contract, flattening into a gigantic disk that spun faster and faster, similar to a skater, which brings its arms closer to the body to spin faster. The Sun formed in the center, and the turbulent gas and dust in the rest of the rotating disk clustered to produce planets, moons, asteroids, and comets. The reason why so many objects are in orbit around the Sun in almost the same plane (called ecliptic) and in the same direction is because they all formed from this same disk.

While the planets were forming, there was little tranquility in our Solar System. Chunks of matter of all sizes would often collide with each other, and they would stick together or touch each other only slightly, taking off pieces and spinning even more. Sometimes the gravity of the larger objects captured the smaller ones within their orbit. This could be a way for planets to get their moons.

Source picture: pixabay

Scientists think that a large object, perhaps the size of Mars, collided with our young planet, removing a piece of material that eventually became our Moon. This collision spun the Earth even faster. Scientists estimate that a day in Earth's first period of life only lasted about 6 hours.

The Moon formed much closer to the Earth than it is today. As the Earth rotates, the Moon's gravity makes the oceans seem to rise and fall. (The Sun also does this, but not so much.) There is a little friction between the tides and the spinning Earth, causing the rotation to slow down a little bit. As the Earth slows down, it allows the Moon to move further away.