Questions tagged [moon]

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

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115
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6answers
14k views

Could we send a man safely to the Moon in a rocket without knowledge of general relativity?

I'm wondering if it's possible to send a man to the Moon using equations consistent with Newtonian gravity and without the elaborate tools of Einstein gravity. Are the predictions made by Newtonian ...
86
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4answers
11k views

Why does a full moon seem uniformly bright from earth, shouldn't it be dimmer at the "border"?

I know the moon is not uniformly grey, it has details, craters, it's not just a colored uniform circle from earth, however, when in a full moon, the intensity of the light received from different ...
81
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9answers
200k views

Why doesn't the Moon fall onto the Earth?

Why doesn't the Moon fall onto the Earth? For that matter, why doesn't anything rotating a larger body ever fall onto the larger body?
62
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4answers
25k views

Why does moonlight have a lower color temperature?

Moonlight has a color temperature of 4100K, while sunlight has a higher color temperature of more than 5000K. But objects illuminated by moonlight don't look yellower to the eye. They look bluer. ...
48
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8answers
73k views

Why CAN we see the new moon at night?

I understand that the Moon's phases are determined by its position in orbit relative to the Sun. (See: Full Story on the Moon). The "shadow" is not cast by the Earth (a common misconception - this is ...
45
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6answers
21k views

Can the apparent equal size of sun and moon be explained or is this a coincidence?

Is there a possible explanation for the apparent equal size of sun and moon or is this a coincidence? (An explanation can involve something like tide-lock effects or the anthropic principle.)
44
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11answers
12k views

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?
41
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7answers
8k views

Why does the full Moon appear?

I know that the full Moon appears when Sun, Moon and Earth are in a straight line, but if we consider that they are in straight line, why is the Moon illuminated? I mean to say that Earth should ...
41
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5answers
27k views

Why is a new moon not the same as a solar eclipse?

Forgive the elementary nature of this question: Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse (...
37
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4answers
159k views

Why does the moon sometimes appear giant and a orange red color near the horizon?

I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
36
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6answers
11k views

If the moon had a mirror surface, would the earth be equally illuminated as by the sun during full moon, or would it require a different mirror shape?

Suppose the apparent diameters of the sun and the moon are exactly the same (which in fact very close to the real situation). If the moon had a perfect mirror surface, would the reflected visible ...
33
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3answers
6k views

Is there a maximum distance from a planet that a moon can orbit?

Given a planet that orbits a star, and a moon that orbits that planet, is it possible to define a maximum orbital radius of that moon, beyond which the moon would no longer orbit the planet, but the ...
32
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3answers
8k views

Why does the Moon face Earth with the same side?

I know that the rotation period of the moon equals its revolution period. It's just so astonishing that these 2 values have such a small difference. I mean, what is the probability of these 2 values ...
26
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1answer
1k views

How can the Moon have such a strong effect on the ocean?

The gravitational acceleration on Earth is approximately $ 10 \mathrm{m}/\mathrm{s}^2 $. Compared to this, the tidal effect of the Moon's gravity gives a local variation in the acceleration of ...
25
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7answers
4k views

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 ...
22
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5answers
18k views

Why is the surface of the Moon white?

Why is the surface of the Moon white? Rather, what makes the surface white?
20
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7answers
5k views

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?...
20
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5answers
2k views

Does the Moon's core still contain significant heat?

On earth, using earth-sheltering techniques can significantly reduce the temperature fluctuations on a structure. Would the same statement be true as well on the Moon? Does the Moon's core still ...
19
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3answers
5k views

How can a full moon be seen south of an observer's location?

I know this seems like a simple question, but I'm trying to debate with a flat earth theorist. I asked him to explain why can the ISS visibly be seen orbiting the Earth with the naked eye, and he put ...
18
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3answers
3k views

I was told that if the Moon had a retrograde orbit, tides would have a faster rhythm. Why is that?

Would this be because tidal deceleration causing the Earth to spin faster or are there other actions in play that I haven't considered? Would the Earth even spin faster because of the tidal ...
18
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2answers
4k views

When will the Moon reach escape velocity?

From what I know, the Moon is accelerating away from the Earth. Do we know when it will reach escape velocity? How do we calculate this?
17
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6answers
10k views

Why can we see the moon when it is between the Earth and the Sun? [duplicate]

A rather stupid question, why can we see the moon when it is between the Earth and the Sun?
17
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6answers
3k views

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 ...
16
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2answers
674 views

What is a "Trojan Moon"?

Today I read an article about Saturn's moon Helene, and it was described as a "Trojan Moon" but no further explanation was given. It was difficult to even get any context about the term from the ...
16
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1answer
409 views

Impact location that created the moon

I was reading an article today about the 1000th orbit of the Lunar Reconnaissance Orbiter, and as many of you know NASA created an animation that simulates the history of the moon. It is speculated ...
15
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3answers
4k views

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 ...
15
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3answers
71k views

The Moon during the day

Why do we see the Moon during the day only on certain days and not every day?
15
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2answers
13k views

How does the central peak in moon craters form?

The central peak in many of the moon's large craters are visible with a telescope and they seem a little odd to me. Can someone explain how they form.
14
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4answers
2k views

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 ...
14
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5answers
11k views

Why do we always see the same side of the Moon? [duplicate]

I am puzzled why we always see the same side of the Moon even though it is rotating around its own axis apart from revolving around the earth. Shouldn't this only be possible if the Moon is not ...
14
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3answers
3k views

Can you drink a glass of lemonade on the moon with a straw?

I don't think it's possible but want to be sure and the exact reason. I don't think it is possible because the atmosphere on the moon is less than one hundred trillionth ($10^{−14} $) of Earth's ...
14
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1answer
2k views

Mars just collided with Earth! A question of eccentricity

One of the standard theories behind the formation of our Moon is the giant impact hypothesis, according to which Earth was struck by a Mars-sized body (about $10\%$ the mass of Earth) early in its ...
13
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2answers
21k views

Is the moon a planet?

Can our moon qualify as a planet? With regard or without regard to the exact definition of the planet, can the moon be considered as planet as Mercury, Venus and Earth etc. not as the satellite of the ...
13
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5answers
27k views

Does the moon affect the Earth's climate?

So, this morning I was talking to a friend about astronomical observations, and he told me that lately there has only been good weather when there was a full moon in the sky, which was a shame. I ...
12
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6answers
7k views

Is the Moon in a "Freefall" Around the Earth? [duplicate]

The force of gravity keeps our Moon in orbit around Earth. Is it correct to say that the Moon is in “free fall” around Earth? Why or why not? I think the answer is yes. The moon is falling towards ...
12
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4answers
2k views

If we were on the Moon would Earth appear to be in motion or at rest?

If we were on the moon would earth appear stationary or would it appear to move. I think it must be stationary because moon is in sychronous rotation with earth.
12
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5answers
9k views

Why does the light side of the moon appear not to line up correctly with the evening sun?

I live at roughly $(52.4^\circ,-2.1^\circ)$. On sunny evenings I've often looked at the Moon and the Sun and noticed that the light part of the Moon does not appear to line up with the Sun. For ...
12
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2answers
737 views

Will Neil Armstrong's moon boot marks really last for thousands of years?

This question concerns the residual heat (if any) contained within the Earth's moon. At the time of the Apollo moon landings, it was widely reported that the boot marks left by the astronauts would ...
11
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2answers
919 views

Where does the dust on the Moon come from?

From the Apollo missions we know that the Moon is covered with dust. Where does it come from? Is it from the erosion of Moon rocks? By what? Or by accretion of dust from space? Which comes from where?
11
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2answers
2k views

Could the earth have another moon?

First, to clarify: I'm not asking if perhaps there's a moon that we haven't found yet. The question is, theoretically, would the earth be able to have another stable moon in addition to the current ...
11
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1answer
887 views

Apollo and orbital mechanics: orbital decay if the Trans Earth Injection (TEI) burn had failed

I'm reading Jim Lovell (Apollo 8 and 13) and Jeffrey Kluger's book Apollo 13, which is a fantastic read about a long past era I only have kindergarten memories of. On page 54 there is a paragraph that ...
11
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1answer
148 views

Why did the june 2011 lunar eclipse last so long?

It was kind of hard to miss the lunar eclipse this week, although I didn't see it in person (Sod's law means that on every relatively major astronomical event clouds cover where I am). From what I ...
11
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1answer
3k views

Observing Jupiter's non-Galilean moons

What strength of telescope is required to observe some of the non-Galilean moons of Jupiter? My current telescope at 50 magnification resolves the Galilean moons well, but I'm guessing it's far ...
11
votes
1answer
506 views

How long will our artifacts last in moon & space?

Given all the different space probes and equipment that have been either launched into space or lying on the moon. How long will they last before they get decayed into dust or some unrecognizable form?...
11
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0answers
333 views

Strange things about new moon [duplicate]

I have some strange and infantile questions about new moon. I want to know how is it possible that the Moon is not visible at night and also at day it is not Sun eclipse? I will explain the problem in ...
10
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2answers
1k views

Different precision for masses of moon and earth online

The Google search page for "mass of moon" shows a value with nine significant digits of precision. The corresponding page for "mass of earth" shows a value with only four significant digits. (The ...
10
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5answers
30k views

Why does the Moon not revolve around the Sun directly?

The sun pulls on the moon with a force that is more than twice the magnitude of the force with which the earth attracts the moon. Why, then, doesn’t the sun take the moon away from the earth?
10
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2answers
2k views

Why don't we see solar and lunar eclipses often?

Since we see the new moon at least once in a month when the Moon gets in between of the Sun and the Earth during the evening ( and as far as I know if this happens during the day, you'll get to see a ...
10
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2answers
8k views

If the moon was twice as big but twice as far away, would there be any difference?

I'm just going to go ahead and steal this question question directly of Reddit since I have more trust in the answers I get on this site. So, if the moon was twice as big but also twice as far way, ...
10
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1answer
2k views

What causes a ring-like image around light of the moon?

I just encountered an interesting image in sky. As you can see in following images there was a ring-like image around light of the moon. I don't know if it was clouds but it was looking like it is far ...

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