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Questions tagged [the-moon]

Questions regarding Earth's only natural satellite. For questions about the natural satellites of other planets, use the tag [natural-satellite].

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73 votes
6 answers
17k views

Why is only one side of the Moon visible from Earth?

Why do we only ever see the same side of the moon? If this is to do with gravity are there any variables which mean we might one day see more than we have before?
Rob's user avatar
  • 849
11 votes
2 answers
4k views

How does the Moon move in the "night" sky as seen from the poles?

A photo in the NYTimes article Ice Surveys and Neckties at Dinner: Here’s Life at an Arctic Outpost has got me thinking. During the winter months at either the north or south pole, when it is ...
uhoh's user avatar
  • 30.7k
19 votes
2 answers
6k views

Why is the Moon receding from the Earth due to tides? Is this typical for other moons?

After reading the Q&A Is the moon moving further away from Earth and closer to the Sun? Why? about the tides transferring energy to the Moon and pushing it from Earth, I have a question: How is ...
user avatar
16 votes
2 answers
4k views

Will the Earth ever be tidally locked to the Moon?

From my basic understating, Momentum is being transfered from the Earth's rotation to the Moon's orbit by tidal friction. The Earth's rotation slows down and the Moon receedes from the Earth as it ...
TheWhaleOnPluto's user avatar
21 votes
1 answer
15k views

Is the moon moving further away from Earth and closer to the Sun? Why?

According to The NASA Moon Facts page: The moon is actually moving away from earth at a rate of 1.5 inches per year. Why is the moon moving further away from the Earth? Is this a result of the ...
user avatar
7 votes
2 answers
489 views

Is there a timekeeping word for the orbit of a moon?

For a planet, we can colloquially refer to its period of rotation as a "day" and its period of revolution around its parent star as a "year." Some worlds have unique terms, such as Martian days being ...
Nerrolken's user avatar
  • 637
4 votes
3 answers
1k views

How to calculate the nodal precession range of the Moon with respect to the celestial equator?

In the span of 18.6 years there is nodal precession of the Moon with respect to the ecliptic of 360 deg. But if we consider this precession with respect to the equator, we will find (unless I'm hugely ...
d_e's user avatar
  • 1,667
37 votes
2 answers
9k views

Why doesn't the moon twinkle?

Stars twinkle because their light has to squeeze through several different layers of the Earth's atmosphere. So why doesn't the moon twinkle as well?
Ricky's user avatar
  • 1,345
26 votes
2 answers
3k views

Is it a coincidence that both the Sun and the Moon look of same size from the Earth?

The Sun is huge, when compared to the Moon. Despite the huge difference in their size and distance from Earth, is it purely coincidental that they both look almost the same from Earth?
Raj's user avatar
  • 371
17 votes
2 answers
18k views

Why can we sometimes see the moon during the day?

At some points in the year, the moon at my location can be clearly visible during the day. Why is this? If it is any help, I live in Alberta, Canada.
aman207's user avatar
  • 375
16 votes
3 answers
7k views

What is the **actual** average distance of the Moon from Earth?

The Moon orbits Earth at a semi-major axis of 384400 km, with its periapsis being 363300 km and apoapsis being 405500 km. (All figures from this NASA fact sheet.) If the Moon orbited Earth at a ...
user177107's user avatar
  • 2,689
11 votes
4 answers
1k views

Why is there no concavity in the orbit of the moon around the Sun?

Such questions have been asked here and I have read the answers some of which are quite informative. However, I want an answer that's straightforward. I have gone through the following paper by A B ...
ThePhysicist's user avatar
10 votes
4 answers
2k views

Red Moon a Characteristic of all Total Lunar Eclipses?

I understand that the redness of the moon during the total lunar eclipse last night/this morning (April 14-15 2014) is a reflection of the red light caused in earth's atmosphere due to Rayleigh ...
NeutronStar's user avatar
  • 2,673
5 votes
3 answers
2k views

Moon's rotation and revolution

Since the moon's period of rotation around its own axis, and that of its revolution around earth is (almost) same, we always see only one side of moon. This is what was, & is taught in schools. ...
Niranjan's user avatar
  • 259
39 votes
4 answers
5k views

Why does the Moon appear gray when passing between the Sun and the Earth?

Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth? The photo was taken by DSCOVR at Lagrange point 1. In the picture, The Moon appears dark gray. Of course the Earth ...
Brian Leeming's user avatar
24 votes
2 answers
2k views

Why does the Moon stablize Earth's axis?

In an academic study titled 'The Moon and the Origin of Life on Earth' it is said that 'If the Moon did not exist, the orientation of the Earth’s axis would not be stable, and would be subject to ...
Kyriakos Kyritsis's user avatar
24 votes
2 answers
5k views

Can you see man-made lights on the dark side of the Earth from the surface of the moon with the naked eye?

This question is prompted from a comment on this answer: Could a person on the surface of the moon see man-made lights on the dark side of the Earth with the naked eye? If not, how much magnification ...
reirab's user avatar
  • 343
18 votes
1 answer
4k 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 ...
Larian LeQuella's user avatar
14 votes
4 answers
9k views

How can I calculate moon phase and height?

How could I know what phase the moon is in when it's high in the sky during sunrise? How could I tell in general what its height in the sky will be at any given time?
JekylHyde's user avatar
  • 329
13 votes
6 answers
27k views

Why doesn't the sun pull the moon away from earth?

If the suns gravitational pull is strong enough to hold much larger masses in place (all the planets) and at much greater distances (all planets further away from the sun then earth) why does it not ...
TheDudeAbides's user avatar
11 votes
2 answers
3k views

Why moon sighted only in Kerala but not in rest of India?

I know for most of you the question may look silly, but Kerala is a state in India where the moon (Ramadan moon) will be sighted but not in rest of India. I was reading the news article where I got a ...
goodyzain's user avatar
  • 213
10 votes
3 answers
2k views

What orbital period would produce one New Moon (and one Full Moon) each year? What other effects would this produce?

I am interested to know whether it's possible for the moon to orbit the earth at such a rate that we would see only one New Moon and one Full Moon a year. If so, what other effects would we experience?...
wallace's user avatar
  • 231
5 votes
1 answer
408 views

Is seeing the Apollo Moon landers via an Earth-based telescope that hard?

There are interferometers that fuse the images produced by multiple telescopes and achieve a resolution of 0.001 arcseconds. With changes, couldn't these observe the Moon landers? Is the reason why ...
user29247's user avatar
4 votes
1 answer
736 views

How much of the sun needs to be blocked in order to see a noticeable drop in brightness

I live in NYC and just experienced the eclipse. What fascinated me the most was that despite the fact that the sun was about 70% blocked, the area was not noticeably dimmer. If the news wasn't saying ...
David says Reinstate Monica's user avatar
77 votes
4 answers
10k views

How does the Earth move in the sky as seen from the Moon?

I just want to be sure I am visualizing this correctly, because it seems odd. The Moon is tidally locked to the Earth but there are wobbles to its motion due to libration. So from a point on the ...
kim holder's user avatar
  • 1,569
31 votes
2 answers
50k views

Is this photocomposition of Andromeda's galaxy and the Moon accurate?

I recently saw the below image circulating around twitter/Facebook/reddit. It is titled "Andromeda's actual size if it was brighter": One of the comments provides a link to another ...
Federico's user avatar
  • 395
27 votes
2 answers
9k views

Where do we have it from that the Moon is migrating away from Earth?

I know Neil Armstrong placed a mirror on the Moon and people shoot lasers there which get reflected, thus measuring the time the light needs they can conclude the current distance of the Moon. But the ...
Ioannes's user avatar
  • 1,090
24 votes
3 answers
10k views

Why is the Moon's orbit so complicated?

I like to think I have a good enough understanding of astrophysics but there's still one thing that I just can't explain. Why does the Moon orbit the Earth the way it does? Many other moons in the ...
ChristieToWin's user avatar
18 votes
6 answers
13k views

Moon's orbit around the Sun

The Earth revolves around the Sun and the Moon revolves around the Earth. Out of curiosity I started thinking about the orbit of the Moon around the Sun and expected (assumed) it to be as follows: ...
Umang Chaudhari's user avatar
15 votes
4 answers
1k views

Why do Earth and moon move apart but binary black holes move closer?

According to the accepted answer on Is the moon moving further away from Earth and closer to the Sun? Why?, the moon is receding from Earth because tidal forces and friction cause energy to be lost. ...
Gnubie's user avatar
  • 663
15 votes
6 answers
9k views

How is this picture of the moon possible?

I need help understanding this images I personally took. If the phases of the moon are determined by the position of the earth, moon & sun. Then how is the moon a crescent while it is rising in ...
Cody Page's user avatar
  • 151
15 votes
2 answers
3k views

Has radio astronomy ever been done on objects that appear very close to the Moon? Is this avoided?

This answer to Which kinds of astronomical observations most need to avoid the Moon being up? mentions For completeness - radio, mid-infrared and mm-wave observations are unaffected (unless the ...
uhoh's user avatar
  • 30.7k
11 votes
2 answers
7k views

Why does the planet Saturn have numerous (62) moons compared to the rest of the planets in the Solar System?

Saturn is a gas giant like Jupiter. It has everything from tiny moonlets less than 1 kilometer across to the enormous Titan, which is larger than the planet Mercury. Saturn has 62 moons with ...
Dr.Ebe's user avatar
  • 119
10 votes
2 answers
2k views

Is the moon's orbit circularizing? Why does tidal heating circularize orbits?

The moon has an elliptical orbit (of course), but as it inches away from the Earth each year, does its orbit become more circular and how come? Io's orbit is becoming more circular due to tidal ...
StellarExile's user avatar
10 votes
1 answer
369 views

How to find Exomoons?

How would we be able to detect Exomoons? We detect exoplanets by seeing if the light gets faint from a star, but could we really use the same method for determining if there is an exomoon around that ...
Dashboarrd's user avatar
10 votes
3 answers
2k views

The moon in the first phase visible in the sky is tilted

I never noticed it before that moon I see in the sky is tilted. Does the tilt of the moon in the sky indicate the direction of the Earth's axis and direction of Earth's rotation around the sun?
Wojciech Domalewski's user avatar
9 votes
3 answers
14k views

Why haven't I seen the Moon?

It has been some time since I've seen the Moon. What are the conditions that might affect whether or not the Moon is visible within a 24-hour period? Please take into consideration any notable ...
Andrew lloyd's user avatar
8 votes
4 answers
895 views

Is there any residual oscillation left from the Moon rotation?

The Moon is tidally locked to Earth - a long time ago it was spinning, but after a time, the spin stopped - two factors stabilizing it: unequal mass distribution creating an equilibrium position where ...
SF.'s user avatar
  • 6,269
8 votes
2 answers
8k views

Where exactly does the Moon flip, given that it appears the other way up in the other hemisphere?

I've read in multiple sources that the Moon appears the other way up in Northern Hemisphere vs Southern Hemisphere. Here is one that explains why: Does the Moon look different in the northern and ...
user69715's user avatar
  • 191
6 votes
1 answer
469 views

When will the last total solar eclipse occur?

Because the moon distance from earth grows, how long will it take, that it is no longer possible to see a total eclipse but only circular eclipses? And does it make a difference if you are on the ...
Luky's user avatar
  • 91
5 votes
5 answers
1k views

Why is this moon red?

I wish I could attach a good quality photograph of this red color moon I'm looking at right now. I searched on internet but there was no lunar eclipse scheduled to occur on 23rd December 2018 in ...
Human's user avatar
  • 71
3 votes
1 answer
157 views

Do we know the fluctuations and constant temperature depth of the moon?

Disclaimer: I have no formal scientific training. From what I understand, surface temperature effects on Earth extend only so far into the ground so that at a certain depth the temperature remains ...
Ruminator's user avatar
  • 187
18 votes
1 answer
33k views

How does the Moon look like from different latitudes of the Earth?

I have heard, that on the northern hemisphere, you can estimate a direction of south if you imagine a line going through the tips of the border between illuminated and shadowed part of the Moon, and ...
user50222's user avatar
  • 281
16 votes
1 answer
3k views

How many times brighter would full-earth-shine appear to people standing on the moon, than full-moon-shine does to people on earth?

The definition of brightness, according to Wikipedia: the term brightness in astronomy is generally used to refer to an object's apparent brightness: that is, how bright an object appears to an ...
Constantthin's user avatar
16 votes
3 answers
2k views

Was lunar libration first observed or first predicted? In either case, who was the responsible party?

How old is the idea of the far side of the Moon? got me thinking that as soon as we see the moon librate we have to come to terms with there being even more of it we can't see. The Moon's libration is ...
uhoh's user avatar
  • 30.7k
15 votes
2 answers
5k views

How bright is the full Earth during the lunar midnight?

At lunar midnight (i.e. the new moon as seen from Earth), the Earth is in its full phase with its entire disk in sunlight, and it is the brightest object in the lunar sky. How bright is it, and how ...
Emilio Pisanty's user avatar
15 votes
2 answers
3k views

Why are most lunar maria on the visible side?

Is there any reason why the Earth side of the Moon has enormous plains and mountains, while the far side contains just few small ones inside largest craters?
SF.'s user avatar
  • 6,269
15 votes
5 answers
4k views

Using parallax to find distance to the moon

I want to use the parallax method (from scratch) to find the distance between the earth and the moon. To get a significant parallax, I need to choose a large baseline. I live in India and my friend in ...
Young Kindaichi's user avatar
13 votes
4 answers
11k views

Is the moon "perfectly" tidally locked and, if not, how long would it take us to observe it's rotation?

I have a general understanding of how and why a body in space can be tidally locked to it's planet or sun and I'm aware that our moon is in such a state. My question is, if our moon once had a ...
RLH's user avatar
  • 375
12 votes
2 answers
9k views

When did the Moon become tidally locked to Earth?

According to various theories the Moon was created around 4.5 billion years ago. About all of these theories suggest that it was rotating around its axis at that time though. Currently, Moon is at ...
SF.'s user avatar
  • 6,269