<p>No.  The orbital speed is related to the distance of the moon by the equation</p>
<p><span class="math-container">$$v=\sqrt{\frac{GM}{r}}$$</span></p>
<p>Where G is a constant, M is the mass of the Earth (adjusted for the mass of the moon) and r is the average distance of the moon(<a href="https://en.wikipedia.org/wiki/Orbital_speed" rel="noreferrer">wikipedia</a>).</p>
<p>So there are two interpretations of your question: firstly what would happen if we gave the moon a big push that doubled its speed? Well this would cause the moon to change its orbit from a roughly circular to an open orbit.  The moon would sail off into space (slowing down as it is dragged back by the Earth, and end up orbiting the sun). The escape velocity is <span class="math-container">$\sqrt2$</span> times the orbital velocity, so if you are in orbit, and double the speed, you are sure to escape.</p>
<p>If you gave it a more gentle push it would enter an elliptical orbit.  The speed would then be non-constant. If you increased its speed by 10% it would move 10% faster at perigee, but slower at apogee and on average its speed would actually be <em>less</em> than before.</p>
<p>The only way to increase the speed is to <em>decrease</em> the distance to the moon.  If you <em>reduced</em> the distance by a factor of 4 (to about 95000km).  This would cause the moon to double its speed.</p>

CC BY-SA 4.0
2020-11-28T17:35:04.527Z
What if you give a push so it moves just 10% faster? 1.1 is lower than sqrt 2
Joe Jobs
CC BY-SA 4.0
2020-11-28T17:44:53.787Z
Edited to discuss a 10% increase in speed.
James K
CC BY-SA 4.0
2020-11-29T21:21:16.957Z
@Joe If you *did* have the resources to double the Moon's orbital speed around the Earth you'd have to apply the required force rather carefully, over a long time span. Otherwise, you're likely to break it &/or melt it.
PM 2Ring
CC BY-SA 4.0
2020-11-30T15:28:15.350Z
Say a satellite is in orbit at 400 km. And then it uses thrusters to raise to 800 km. That means the satellite will reduce its linear speed simply because it raised its orbit? How can that happen? It is counter intuitive. Basic logic says it needs to fire thrusters in opposite direction to lose speed
Joe Jobs
CC BY-SA 4.0
2020-11-30T19:17:38.983Z
Yes! it is very counter intuituve.  But that is what happens.  You fire your thrusters to push you forward faster, and the result is you move to a higher orbit going slower!  Yes this is what happens.  It seems counter intuituve, but this is what happens
James K
CC BY-SA 4.0
2020-11-30T19:21:43.047Z
You are in an orbit at 400km, you fire a burst of thrusters, increasing your linear speed.  You then glide out, slowing down until you reach 800km,  you are now going **much** more slowly, so you fire another burst of thusters to get into a circular orbit.  You have increased speed again, but your final speed is still slower than when you started.
James K
CC BY-SA 4.0
2020-11-28T17:27:31.260Z
2020-11-28T19:21:00.693Z
2020-11-28T19:21:00.693Z
James K
<p>If the Moon would rotate around the Earth with double its current speed.</p>
<p>What would happen then?
Would it get further from the Earth or it would be possible to keep its distance from Earth?</p>

CC BY-SA 4.0
2020-11-29T18:53:22.677Z
Why has this question been downvoted?
Jim421616
CC BY-SA 4.0
2020-11-29T21:16:15.313Z
@Jim421616 Impossible hypothetical scenario questions are generally off-topic here. But I think this question is ok since it's (mainly) just asking about basic celestial mechanics.
PM 2Ring
CC BY-SA 4.0
2020-11-30T04:53:55.567Z
Can you clarify your question regarding "twice as fast".  Orbital mechanics work such that as bodies orbit faster, they need to have a higher orbit.  But the higher orbit has more distance to cover and that means that while moving "faster" they require more time to complete a full orbit.  Are you referring to the velocity ... or the period of the orbit taking half as long to complete an orbit?
Tim Campbell
CC BY-SA 4.0
2020-11-30T07:01:55.013Z
@TimCampbell no orbital mechanics works such that as bodies orbit faster they need to have a lower orbit.
James K
<the-moon>
What happens if the Moon moves twice as fast?
Joe Jobs
# What happens if the Moon moves twice as fast?

(Asked by: username_0 on 2020-11-28)

If the Moon would rotate around the Earth with double its current speed.

What would happen then?
Would it get further from the Earth or it would be possible to keep its distance from Earth?

**Tags:** the-moon
> **Comments:**
> **username_1**: Why has this question been downvoted?  
> **username_2**: @Jim421616 Impossible hypothetical scenario questions are generally off-topic here. But I think this question is ok since it's (mainly) just asking about basic celestial mechanics.  
> **username_3**: Can you clarify your question regarding "twice as fast".  Orbital mechanics work such that as bodies orbit faster, they need to have a higher orbit.  But the higher orbit has more distance to cover and that means that while moving "faster" they require more time to complete a full orbit.  Are you referring to the velocity ... or the period of the orbit taking half as long to complete an orbit?  
> **username_4**: @TimCampbell no orbital mechanics works such that as bodies orbit faster they need to have a lower orbit.  

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## 1 answers

### Answer by username_4 on 2020-11-28. Score: 11

No. The orbital speed is related to the distance of the moon by the equation

$$v=\sqrt{\frac{GM}{r}}$$

Where G is a constant, M is the mass of the Earth (adjusted for the mass of the moon) and r is the average distance of the moon([wikipedia](https://en.wikipedia.org/wiki/Orbital_speed)).

So there are two interpretations of your question: firstly what would happen if we gave the moon a big push that doubled its speed? Well this would cause the moon to change its orbit from a roughly circular to an open orbit. The moon would sail off into space (slowing down as it is dragged back by the Earth, and end up orbiting the sun). The escape velocity is $\sqrt2$ times the orbital velocity, so if you are in orbit, and double the speed, you are sure to escape.

If you gave it a more gentle push it would enter an elliptical orbit. The speed would then be non-constant. If you increased its speed by 10% it would move 10% faster at perigee, but slower at apogee and on average its speed would actually be *less* than before.

The only way to increase the speed is to *decrease* the distance to the moon. If you *reduced* the distance by a factor of 4 (to about 95000km). This would cause the moon to double its speed.

> **Comments:**
> **username_0**: What if you give a push so it moves just 10% faster? 1.1 is lower than sqrt 2  
> **username_4**: Edited to discuss a 10% increase in speed.  
> **username_2**: @Joe If you *did* have the resources to double the Moon's orbital speed around the Earth you'd have to apply the required force rather carefully, over a long time span. Otherwise, you're likely to break it &/or melt it.  
> **username_0**: Say a satellite is in orbit at 400 km. And then it uses thrusters to raise to 800 km. That means the satellite will reduce its linear speed simply because it raised its orbit? How can that happen? It is counter intuitive. Basic logic says it needs to fire thrusters in opposite direction to lose speed  
> **username_4**: Yes! it is very counter intuituve.  But that is what happens.  You fire your thrusters to push you forward faster, and the result is you move to a higher orbit going slower!  Yes this is what happens.  It seems counter intuituve, but this is what happens  
> **username_4**: You are in an orbit at 400km, you fire a burst of thrusters, increasing your linear speed.  You then glide out, slowing down until you reach 800km,  you are now going **much** more slowly, so you fire another burst of thusters to get into a circular orbit.  You have increased speed again, but your final speed is still slower than when you started.  

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