- #1
avito009
- 184
- 4
I know that Earth orbits the sun because it has initial momentum and that prevents it from falling into the sun. But does moon that orbits the Earth also have initial momentum?
In summary, the conversation discusses the concept of initial momentum and its role in the orbits of the Earth and the Moon around the Sun. While the Earth and Moon are generally thought of as a single object orbiting the Sun, there are exceptions where smaller satellites can have a "horse shoe" shaped orbit that lies near the Earth's orbit. This raises the question of how to classify the orbit and whether it is worth the trouble to do so.
- #2
Drakkith
Mentor
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I don't know what 'initial momentum' is. As far as I understand, both the Earth and the Moon have angular momentum which they would need to get rid of in order to fall into the Sun.
- #3
dean barry
- 311
- 23
I aways imagine the Earth and moon as a single item orbiting the sun
- #4
Drakkith
Mentor
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dean barry said:
That is indeed one way you can imagine it if you aren't worried too much about accuracy.
- #5
sophiecentaur
Science Advisor
Gold Member
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That's how we mostly think of it. However, the situation can arise where you get a so called 'horse shoe' orbit where the orbit of a small satellite follows a horse shoe shaped path which lies near to the Earth's orbit. There are a number of asteroids that actually do this. See this Wiki link. It is a moot point whether you would consider the satellite as orbiting around the Earth or the Sun. This could be another example of where insisting on classifying the orbit as one or the other is more trouble than it's worth.dean barry said:
1. Why does the moon orbit the sun?
The moon orbits the sun because of gravity. The sun's strong gravitational pull keeps the moon in its orbit, just like how the earth's gravity keeps the moon in its orbit around the earth.
2. Does the moon orbit the sun at a constant speed?
No, the moon's speed is not constant as it orbits the sun. Its speed varies depending on its position in its orbit. The closer the moon is to the sun, the faster it moves, and the farther it is from the sun, the slower it moves.
3. How long does it take for the moon to orbit the sun?
The moon takes about 27.3 days to complete one orbit around the sun. This is known as its sidereal period, which is slightly longer than its orbital period around the earth (which is 27.3 days).
4. Why does the moon always have the same side facing the earth?
The moon's rotation is synchronized with its orbit around the earth, which causes it to always have the same side facing us. This is known as tidal locking and is a result of the earth's gravity causing the moon's rotation to slow down over time.
5. Can the moon's orbit around the sun change?
Yes, the moon's orbit around the sun can change over time due to various factors such as the gravitational pull of other planets, solar wind, and the moon's own gravitational pull. However, these changes are very small and happen slowly over time.
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