Why is the moon not attracted by earth?
We have been observing the moon since we were little and while many things have changed, the moon has remained constant. While it might appear to change its shape occasionally, it has never changed its position. The moon might not appear for a couple of nights but then it always makes an appearance again, coming back in its full glory. So there might be a question, that many of you would have in the back of your minds, why does the never fall on earth? What is it that keeps the moon away from earth? Well let us try and explain this phenomenon.
Gravity is a very fascinating topic in physics. As children we might have thought it is some kind of magic. But the reality is, it is just science. Let us have a brief into the reasons behind why the moon is not falling onto earth and how it continues to maintain perfect distance and equilibrium with earth. There is a strong gravitational force between the earth and the moon. So then, why isn’t it attracted to the planet earth? This is because the gravitational force isn’t intense enough to pull it to earth.
Gravity
As a child, even we used to think it was some magic, but we hate to break it to you, that's not magic, it's science. This is relatively close to magic, and today, we are going to talk about how the moon is not attracted to Earth and how we are safe from getting hit by the moon anytime soon.
Instead of asking why the moon doesn't fall on Earth, you need to ask Why the moon is not attracted to Earth? This is a better way to put words to this question. The gravitational force between Earth and the moon is strong. But the force is not strong enough to pull the moon towards us, like an apple falling from the tree due to Gravity.
What Keeps the Moon in Orbit Around the Earth?
From Earth, it might look like the moon is stationary, meaning it is not moving, but in reality, each year the moon gets 3 cm away from Earth. Without having the force of Gravity from earth-moon would have just floated away from us. The moon's velocity and distance from Earth allow it to make a perfect balance between fall and escape.
In case the velocity of rotation of the moon was a little bit faster, it would have escaped the Earth's Gravity. On the other hand, if it's a little bit slower, it would have fallen on Earth. That's why the moon doesn't fall on Earth.
What Happens if Earth Doesn't Have Gravity?
We have told you about how Gravity depends on the distance too. You might have seen Astronauts in the space they are floating inside the space station and when they are doing the spacewalk. That's a clear example of humans able to escape the Gravity of Earth. It does take a lot of energy to leave the Earth's atmosphere and then go to space. But once you are in space, no force is holding you back from flying like a Superman.
On the other hand, there is a downside of not having any Gravity. If on Earth we don't have Gravity, the Earth won't be present in the first place. The big chunks of it will break and float away in space. In addition to this, if somehow Earth managed to keep itself together still, there will be no water and atmosphere on the surface of the Earth, and thus, no living organism will be able to survive such a harsh environment.
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Furthermore, if we were somehow able to live on Earth, our bodies will have no shape, meaning the body structure that you see right now in all animals will not be present. Yes, you will be like Jelly, and your bones and organs will move inside your skin from place to place. We are sure nobody wants to have that kind of experience.
To keep their muscles intact, astronauts in space take more than 3 hours of daily exercise routine. Even after all this exercise, astronauts still need rehabilitation to get back on their feet to move around freely. One more thing we would like to tell you, with massive Gravity comes time travel. Yes, we are not joking here. A Russian cosmonaut named Sergei Krikalev spent 803 days on a space station revolving around the Earth. The gravity pull on the space station was less compared to the pull that we have on Earth. As a result, Krikalev lived 0.02 seconds less than everyone on Earth.
This is the only way we can time travel right now. If an object is big and has a massive gravitational pull, then time around that object will slow down. This was also depicted in Interstellar, a Sci-fi movie by Cristopher Nolan, who showcased how time affects a person when they get close to Blackhole.
What is the reason behind the moon remaining in the orbit surrounding the earth?
From the position of the earth, it might appear that the moon is stationary, however the fact is the moon keeps getting 3 cm away from the earth every year. Without the force of gravity, the moon would have just vanished away from us. The moon’s distance from earth and its velocity enables the striking of the perfect balance between crashing to earth and escaping away. If the velocity of the moon’s rotation was a bit faster, then it would have managed to escape the gravity of earth. And if the velocity was a bit slower, then the moon would have crashed on earth. The fact is it is neither and the velocity is just right for it to stay where it is.
The gravity of earth is an important factor in keeping the various planetary bodies and objects the way they are. So for instance if earth didn’t exhibit any gravity, then it wouldn’t exist in the first place. Without gravity massive chunks of earth's surface will break and just float away down the space. Even beyond that, without gravity there will be no atmosphere or water on the earth’s surface and as a consequence no living being would be able to survive this harsh environment.
FAQs on Why Doesn't The Moon Fall Into The Earth?
1. What prevents the Moon from falling into the Earth?
The Moon is prevented from falling into the Earth by a perfect balance between two forces: Earth's gravitational pull and the Moon's orbital velocity. Earth's gravity constantly pulls the Moon inwards, acting as a centripetal force. At the same time, the Moon has a high forward speed (tangential velocity) that tries to make it travel in a straight line. This forward motion continuously makes the Moon "miss" the Earth as it falls, resulting in a stable orbit.
2. Why doesn't the Moon fall to Earth like an apple from a tree?
The Moon is actually always falling towards Earth, just like an apple. The key difference is that the Moon has a significant sideways velocity. An apple falls straight down because it has no sideways motion. The Moon's high speed means that as it falls towards Earth, it also travels a great distance horizontally. This continuous falling and moving sideways is what creates its orbit, causing it to perpetually circle around the Earth instead of crashing into it.
3. What is the role of centripetal force in the Moon's orbit around the Earth?
In the Earth-Moon system, the force of gravity is the centripetal force. This force is essential as it continuously pulls the Moon towards the centre of its orbit (the Earth). Without this constant inward pull, the Moon's inertia would cause it to fly off in a straight line into space. The centripetal force is what constantly changes the Moon's direction, bending its path into a stable orbit.
4. If the Moon's gravity pulls on the Earth, why doesn't the Earth move towards the Moon?
The Moon's gravity does pull on the Earth with a force equal to what the Earth exerts on the Moon. However, the Earth has approximately 81 times more mass than the Moon. According to Newton's Second Law of Motion (F=ma), the same force will cause a much smaller acceleration on a more massive object. Therefore, the Earth only experiences a slight "wobble" as both bodies orbit a common centre of mass, known as the barycenter, which is located inside the Earth itself.
5. Why do we always see the same side of the Moon from Earth?
This phenomenon is called synchronous rotation or tidal locking. Over billions of years, Earth's gravity has slowed the Moon's rotation to the point where its rotational period is the same as its orbital period. The Moon takes about 27.3 days to rotate once on its axis and the same amount of time to complete one orbit around the Earth. As a result, the same hemisphere of the Moon is always facing our planet.
6. How does the Earth's orbit around the Sun relate to the Moon's orbit around the Earth?
The physical principle governing both orbits is exactly the same: a balance between gravity and velocity.
- Earth-Sun System: The Sun's immense gravitational pull provides the centripetal force that keeps the Earth from flying away. The Earth's high orbital velocity prevents it from falling into the Sun.
- Earth-Moon System: The Earth's gravity provides the centripetal force for the Moon's orbit, while the Moon's orbital velocity keeps it from falling into the Earth.
7. What would happen if the Moon suddenly stopped moving in its orbit?
If the Moon's orbital velocity suddenly became zero, there would be no outward force to counteract Earth's gravity. The centripetal force provided by gravity would be unopposed, and the Moon would begin to fall directly towards the Earth. It would accelerate as it got closer, eventually leading to a cataclysmic collision with our planet.
