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].
161
questions
72
votes
6
answers
16k
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?
- 839
20
votes
2
answers
5k
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 ...
- 1,576
11
votes
2
answers
3k
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 ...
- 31.1k
15
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 ...
- 151
22
votes
1
answer
14k
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 ...
user96
7
votes
2
answers
405
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 ...
- 617
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?
- 1,271
25
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?
- 361
17
votes
2
answers
17k
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.
- 375
10
votes
3
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 ...
- 2,583
5
votes
3
answers
581
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. ...
- 259
4
votes
3
answers
546
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 ...
- 1,637
37
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 ...
- 481
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 ...
- 343
23
votes
1
answer
1k
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 ...
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?
- 329
13
votes
6
answers
25k
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 ...
- 351
11
votes
4
answers
877
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 ...
- 275
11
votes
2
answers
2k
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 ...
- 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?...
- 231
4
votes
1
answer
169
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 ...
74
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 ...
- 1,539
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 ...
- 1,052
24
votes
3
answers
7k
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 ...
- 888
17
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 ...
- 1,434
16
votes
6
answers
10k
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:
...
- 163
15
votes
3
answers
6k
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 ...
- 2,413
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 ...
- 31.1k
10
votes
2
answers
1k
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 ...
- 881
10
votes
1
answer
348
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 ...
- 485
9
votes
3
answers
12k
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 ...
- 101
8
votes
4
answers
797
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 ...
- 6,157
7
votes
2
answers
7k
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 ...
- 181
6
votes
1
answer
339
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 ...
- 91
3
votes
1
answer
223
views
Is seeing the apollo moon Landers via earth telescope that hard?
There are interferometers, which are combining multiple telescopes together, with 0.001 arcsecond resolution. With changes, couldn't these observe the Landers? Is the reason why nobody is seeing the ...
- 41
3
votes
2
answers
211
views
Does a lunar occultation of Mars happen twice a year?
The Space Exploration SE question When our Moon is hiding Mars, is it possible to create a radio communication between Earth and Mars? links to this short article in the popular press Mars is hiding ...
- 31.1k
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 ...
- 31.1k
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 ...
- 475
16
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.
...
- 533
15
votes
6
answers
8k
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 ...
- 151
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?
- 6,157
13
votes
4
answers
10k
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 ...
- 375
12
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 ...
- 2,033
11
votes
2
answers
8k
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 ...
- 6,157
9
votes
2
answers
3k
views
Can I measure the moon's gravity?
Since I learned about Newton's gravity law, I wonder if I can measure the moon's gravity using (almost) no special equipment. The best I could come up with is a pendulum, which is in a resting ...
- 269
9
votes
2
answers
11k
views
Why can I see the whole moon during various non-full-moon phases?
Here's an image that describes the phenomenon I'm asking about. The very thin sliver to the left is of course the surface of the moon as lighted by the sun. But the rest of the moon is also faintly ...
- 193
8
votes
2
answers
1k
views
Can Earth host another natural satellite than the Moon?
Are there orbits with long-term stability (astronomical time scales) around Earth? Low altitude orbits will decay due to friction with Earth's atmosphere. Inside Earth's Roche limit, a Moon could not ...
- 763
7
votes
3
answers
1k
views
Implementation of formulae for Meeus for the Moon
With Astronomical Algorithms by J. Meeus (1998)
I have obtained the relevant illuminated fraction of the disk and position angle.
But they're numbers (all Greek to me!) I know, Meeus explains that ...
- 182
6
votes
1
answer
452
views
How fast was the Earth spinning directly after the Moon formed?
I understand the Moon was perhaps five Earth radii away when it first formed (assuming it was formed by a giant impact of a Mars-sized body), and Earth has since transferred its rotational energy into ...
- 394
5
votes
1
answer
224
views
How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?
Wikipedia's opposition surge is a short article and forwards shadow hiding and coherent backscattering as proposed mechanisms, but it doesn't really explain how much the brightness of the Moon ...
- 31.1k