Questions tagged [moon]

A smaller body orbiting a larger, primary body, where the primary body is not a star.

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Are there any moons that exhibit a non-convex curvature in their orbit about the Sun?

In my answer at https://physics.stackexchange.com/a/266444/59023, it took me several iterations before David Hammen and others could help me understand why the Earth's moon's orbit about the Sun is ...
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Why Moon is not falling on Sun (Hill's sphere)?

The Hill's radius of Earth in Earth-Moon system calculated by formula https://en.wikipedia.org/wiki/Hill_sphere is 58212 km But the distance between Moon and Earth is 384,400 km So, why Moon is not ...
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What is the relationship between crescent moon and position of the sun? [duplicate]

This is a phenomenon that involves the angles between the points of a crescent moon and the apparent position of the sun. Step outdoors on a day and time when you can see the sun and a crescent ...
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Earth, Moon, gravitatioal pull

Does the gravitational pull that causes tides, also affect the Earth's land mass. Does it affect the atoms, molecules, is there a slight bulge to the actual Earth / Land itself?
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Could the moon's centrifugal force generate the same acceleration as 9.8 m/s$^2$? [closed]

If one dug into the moon, could one reach a point where the centrifugal force is close to that of Earth's gravitational pull? If so, how deep would one have to dig? If not, how close could one get to ...
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Distance of the Moon Cycles

Recently, I started to search more about the orbit of the moon, and noticed there are certain periodic patterns or cycles for which I did not find any satisfactory explanation. The first cycle can be ...
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Moon gravity space low gravity [closed]

How is it possible that a man or woman without equipment will "float" on the moon, but a photo can be left lying on the surface without anchor and not float away?
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Should the Rayleigh scattering of blue light somehow 'paint' the Moon image in the sky slightly in blue?

Should the Rayleigh scattering of blue light somehow 'paint' the Moon image in the sky slightly in blue? Maybe the Moon light is too intense during the day for that kind of effect to take place as ...
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Is it a coincidence that distance between Sun and Earth=(Distance between Earth and Moon)*(365.25+24) or is there any logical reasoning behind it? [closed]

Here $365.25$ days is the time taken for Earth's Revolution around the Sun while $24$ hours is the Earth's rotation.
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What would happen if I shot a near-light-speed bullet at the moon? [closed]

What would happen if I shot a bullet at 90% of light speed from earth to the moon? Would it make it through the atmosphere? Would it have any negative effects on the earth's atmosphere as it passes ...
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If you sliced the moon in half perfectly, would it hold together?

Just a big ol' slice down the middle. Would it drift apart over time, or eventually fuse back together?
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What is the logic behind this vis viva equation based calculation?

"If the moon were shrunk to having a radius of one meter, without changing its distance (of the apogee) from the earth, what would be the slowest it could be slowed down to and still orbit the ...
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If you could shrink the moon to one meter radius, how much could you slow the moon down by and have it continue to orbit the earth? [closed]

If the moon were shrunk to having a radius of one meter, without changing its distance (of the apogee) from the earth, what would be the slowest it could be slowed down to and still orbit the earth, ...
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Does the solar wind blow *through* the moon's atmosphere/exosphere?

The Wikipedia article on "Atmosphere of moon" says: One source of the lunar atmosphere is outgassing: the release of gases such as radon and helium resulting from radioactive decay within ...
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How much of the Tidal Energy can be attributed to the Sun?

I'm been researching this question but haven't been able to find a conclusive answer. As I understand it, there are two forms of tidal energy: tidal potential energy and tidal current energy. Tidal ...
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What does "rarely" mean in NASA's statement: "technically referred to as an exosphere because it’s so thin, its atoms rarely collide."?

The following statement is from this article: The behavior of a dense atmosphere is driven by collisions between its atoms and molecules. However, the moon's atmosphere is technically referred to as ...
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Could a balloon be thrown from the moon to the earth by a man or woman or machine?

Is it physically possible for a three meter radius balloon to be whirled about on a string by a person or if necessary a machine (perhaps held by the person) standing on the surface of the moon and ...
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Why the blue component of the moonlight is less scattered in Earth's atmosphere than the sunlight?

Why the blue component of the moonlight is less scattered in Earth's atmosphere than the sunlight? So when rising one of them looks yellow and the other red. Is this only matter of their brightness ...
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Why don't we ever see an astronaut in a vacuum with a balloon? [closed]

Is there any physical reason why don't we ever see an astronaut in a vacuum with a balloon? A balloon weighs so little, and so it wouldn't cost much to bring one into orbit, or even to the moon. They ...
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How can you show that the Moon's gravity is one sixth of the Earth's? [closed]

I've tried using \begin{equation} F_s = \frac{GMm}{d^2} \end{equation} but I got this answer: $1.8704 \times 10^{20} $ I'm not sure what I'm doing wrong?
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Would Foucault's pendulum work on the moon?

I am taking a course in introductory general relativity and came up on this question, which a google search didn't answer. The rotation of the Earth can be measured using a Foucault pendulum. The moon ...
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Is there a correlation between the Earth's spin, the moon, and temperature?

Based on NASA's arcticle, changes to land, ice sheet, ocean, and mantle flow affect Earth's spin. Does the moon's elliptical orbit around Earth also affect Earth's spin? What effect does distance play?...
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Will a satellite orbiting the moon have a tidal locked orbit?

Suppose an artificial satellite is launched to orbit the moon. Ignore 3-body problem issues, just assume it follows a roughly titled elliptical orbit relative to the plane cutting through earth's ...
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1answer
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Why are the Earth and Moon so different?

The suggestion was made that the Earth and the Moon are two parts of a once whole object. If that is true then they must share the same basic composition. They also receive fairly similar amounts of ...
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Why didn't the debris collapse back into the Earth at the time of Moon's formation?

The most accurate theory for the formation of our moon is the Giant impact hypothesis, which says that a Mars sized body collided with our early Earth and after this collision all the debris got ...
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The role of the Sun in spring and neap tides

I am trying to understand how the Sun affects tides on the Earth's oceans and seas. It is quite clear that when the Moon is in the first and in the third quarter, the Sun's and the Moon's ...
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Rate of potential vs. rate of kinetic energy on the moon

If I was on the moon and threw a tennis ball upwards, how would the ball's rate of potential energy $U$ compare to its rate of kinetic energy $K$? I understand the concept when it's on the earth, but ...
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If the moon became a black hole, how much lower would the temperature be on Earth's surface?

I read that if the Sun became a black hole the Earth would become colder, but the effect would be negligible because the mass of the hole is still there so there would still be tides. But, how much ...
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In the difference between the sun and moon's tidal effects on earth, is density or distance a larger factor?

This question is inspired by the (now looking at it, improper use of, my bad) comments section here in Physics SE. I'm not sure I could explain better than our short discussion does below: No, the ...
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Venus light rainbow

I have recently been quite amazed to learn that rainbows produced by moonlight (or moonbows) can sometimes be bright enough to be seen (not with the naked eye though). Now I wonder, would there be any ...
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Measuring Sun and Moon distances to the Earth ratio just by observing angles of elevation if upper 50 percent of Moon's surface is bright?

When the next type of calculation was possibly used for the first time? If 50% i.e. upper half of Moon were bright would the Sun-Earth to Moon-Earth distances ratio be calculated from just ...
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THE LINE OFTHE MOONLIGHT IS NOT STRAIGHT ANYMORE [closed]

I am from the USA, just a retired soldier who looks at the sky a lot. This morning 26 SEP 2020 at 1am, the Moon was approximately a quarter Moon. It was bright, the line/shadow on the moon was not ...
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How much the Earth atmosphere oscillates due to Moon tidal force and does this produces winds?

As there is the tidal force of the Moon exerted on the Ocean water I supose there must be some force acting to the Earth's atmosphere. So when the atmosphere starts falling down as the Moon is ...
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If the moon had always been a black hole (with the same mass) when and how would we have realised? [closed]

Inspired by this recent question. If, sometime shortly before writing was invented, some passing alien turned the moon into a tiny black hole (xkcd) when/how/would we have figured out it was there, ...
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If the moon became a black hole, how much would it eat in a day?

I have been thinking about the moon becoming a black hole. I was thinking about how much it would eat a day. How much mass would it suck in in 24 hours on average? I am writing a story where the moon ...
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Can tidal locking increase rotational kinetic energy? Where does the energy come from then?

I was thinking about the explanation for how the Moon gets tidally locked with the Earth. We are working in the non-rotating reference frame of the Earth, and assume it is inertial (to an approximate ...
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How much does $g$ vary according to the position of the moon?

The gravity of the earth or more specifically the gravitational acceleration, $g$, is the acceleration objects with mass experience toward the earth due to gravity. How much does this vary according ...
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Why does the moon sometimes look reddish yellow?

So the question is clear from the title itself. Only sometimes does the moon when it just rises above the horizon, looks reddish in colour. This mostly as I have seen occurs when the moon rises when ...
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If Saturn's rings cannot coalesce into a moon because of tidal forces, then how are shepherd moons able to exist?

From Wikipedia: In celestial mechanics, the Roche limit, also called Roche radius, is the distance within which a celestial body, held together only by its own force of gravity, will disintegrate due ...
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What's the UV index on the Moon

What would the UV index be on the moon compared to the Earth? I'm pretty sure it would be ridiculously high but I'm not sure how high.
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How big a coincidence is the Sun and Moon having almost equal apparent sizes?

It's consensus that the very similar apparent sizes of the Moon and the Sun as seen from Earth is a coincidence (as already answered in this site). This provides us with almost exact total solar ...
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What will be the absolute gravity of Io moon if Jupiter's gravity not in effect? Can GR explain it?

It is noted that the distance between Io moon to Jupiter planet and our Moon to Earth is nearly same. However, the ratio of gravity Earth/Moon is 80.4 times vs ratio of gravity Jupiter/Io is 20276.7. ...
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I want to know about the synodic and sidereal months. Why is there a difference between the two? [closed]

I want to know about the synodic and sidereal months. Why is there a difference between the two?
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Could a planets magnetic field magnetise the core of its own moon?

Could a planet with a magnetic field make the core of its moon (or another celestial body), if it was made of iron say, into a giant permanent magnet?
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Why do we use $F=GMm/r^2$ when calculating the centripetal force of the moon around the Earth and not $g=GM/r^2$? [closed]

When we calculate the centripetal force of a satellite orbiting earth, we use $g=GM/r^2$, implying that gravitational force and centripetal force are the same. However, when calculating the ...
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What is a simple argument to prove that the stars in the sky are further away from the Earth than the Moon?

How do we know, without using modern equipment, that the stars are further away than the moon in the night sky? Further, is there a simple and actionable argument to prove that this is indeed the case?...
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What is the reason for assuming angular momentum is conserved for a moon-planet system where the moon is in an elliptical orbit around the planet?

I came across a question in the Princeton Review book for AP Physics 1 and then found the same question in the Collegeboard AP Physics course guide. Both have different answers. (See the questions ...
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Harvesting energy from Moon's orbit without water [closed]

We use the gravitational interaction between the Sun, Moon, and Earth to harvest energy from the motion of the oceans, the tidal "bulge", along coastlines. This uses the changing sea level to ...
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What is the interplay between the "spinning tennis racket" effect on a planet with three principle axis of rotation and its moon?

Suppose I have a tennis racket spinning on its second axis of rotation such that it is subject to periodically flipping over on its spinning axis, as per the Dzhanibekov effect (explained in ...
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How does our Moon stay in orbit around Earth? A question about gravitational field strength [duplicate]

Calculating the gravitational field strength felt by our Moon, caused by our Earth and Sun, I found that the magnitude of the Sun's gravitational field is felt as greater by the Moon than the Earth's. ...

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