by Curious Kids is a series for children of all ages. If you have a question you want to answer from an expert, send it to curiouskidsus@theconversation.com.
“Is the moon further removed from the earth?” – Juda, 9, broken arrow, Oklahoma
The moon gets 3.8 centimeters away from the earth every year.
Scientists measure the distance to the moon by bouncing lasers that are placed there by space probes and astronauts.
Due to the measurement of the time that lights need to travel to the moon and back, scientists can measure the distance to the moon and change the distance very precisely.
The distance to the moon actually changes over a month when it goes around the earth. The moon is typically 385,000 km away from the earth, but its orbit is not a perfect circle and changes by 20,000 km because it circulates the earth. This change is the reason why some full moons are slightly larger than others. These are referred to as super moon.
As astrophysics researchers, I am interested in the movement and interaction of objects such as planets, stars and galaxies. The movements of the earth and the moon have many interesting consequences, and studying how they move over time can help the researchers better understand how everyone has changed in the 4½ billion years since earth and moon was founded.
Tidal forces
Why is the moon going away? It’s all because of tides.
Tides come from a difference in gravity via an object. The gravity exerted by the moon is about 4% stronger on the side of the earth, which is directed towards the moon, compared to the opposite side of the earth side, since gravity becomes weaker with the distance.
This tidal force lets the oceans swell around in two outlets that indicate and away to the moon. They do this because the gravitational force that pulls on the moon on earth is not just an average force that is the same strength everywhere. The gravity of the moon is the most powerful on the nearby side of the earth and creates a bay of water to point to the moon. It is weaker on the opposite side of the earth, which leaves a further bortage of water behind the rest of the earth.
While the earth turns, these boosts move and continue to point to the moon because they are pulled at the gravity. In New York City or Los Angeles, the water level can change by about 5 feet due to this tidal building.
These liquid outbursts are not entirely directed with the moon – they “lead” it a little because the earth turns and drags forward. These outfit also exert a gravitational suit on the moon. The bay closer to the moon not only pulls the moon towards the earth in the earth, but also a bit in front of me in its orbit – like the thrust that a sports car gets when it comes to a curve.
This forward train from the closer tidal remuneration means that the moon is accelerated, which means that the size of its orbit increases. Think of a baseball player who hits Homerun. When the player hits the ball faster on the home board, he will be enlarged to the sky.
The conclusion is that the gravity of the closer tidal curvature on earth pulls the moon forward, which increases the size of the lunar orbit. This means that the moon is a little further away from the earth. This effect is very gradually and on average only detectable for years.
Does the increasing removal of the moon influence the earth?
The moon gains momentum when its orbit increases. Think about turning a weight attached to a cord. The longer the cord, the more swing the weight has and the more difficult it is to stop.
Since the earth does the work to increase the impetus of the moon, the rotation of the earth slows down around the row because its dynamic goes to the moon. In other words, when the moon’s orbital impulse increases, the rotation impulse of the earth decreases in exchange. This exchange makes a day a little longer.
But don’t worry, these effects are so small: 1.5 inches a year compared to a distance of 239,000 miles (384,000 km) only 0.0000,0001% per year. We will always have solar eclipses, tides and days that take 24 hours for millions of years.
Was the moon closer to us in the past?
The earth’s days were shorter in the past.
The moon probably formed around 4.5 billion years ago when a young earth was hit by a protoplanet in Mars size, which caused a lot of material to be thrown into space.
After all, this material formed the moon, and it was much closer to the earth at first. At that time they would see the moon in the sky much larger.
By investigating petrified mussel shells on material that shows its daily growth patterns, paleontologists found that 70 million years ago – towards the end of the dinosaurs – the day lasted only 23.5 hours, just as predicted by astronomical data.
What will happen in the future?
So will the moon escape in front of the earth’s path when it moves away?
If we are going forward umpteen billions of years in the future, the rotation of the earth could finally slower until it is neatly connected to the moon. This means that it would take just as long for the earth to rotate like the moon to surround. At this point, the moon would stop becoming more distant, and they would only see the moon from the earth from the earth.
But two things will prevent that. First, the sun is brighter in about billion years and the oceans are cooked away. Then there are no large tidal water so that the moon is further removed. A few billion years later, the sun will expand into a red giant and probably destroy the earth and the moon.
But these events will be so far in the future that they don’t have to worry about them. You can simply enjoy tides on the beach, solar eclipses and our beautiful moon.
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This article will be released from the conversation, a non -profit, independent news organization that brings you facts and trustworthy analyzes to help you understand our complex world. It was written by: Stephen Dikerby, Michigan State University
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Stephen Dikerby receives funds from the NASA and NSF subsidies as well as from the Michigan State University.
