# 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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### What's the first written record of the moon being tidally locked to the earth?

I couldn't find references as to who first noticed (wrote down) that the moon was tidally locked to the Earth. This, to me, doesn't seem obvious from first glance, and looks like something only found ...
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### If the earth lost 1/81th of its mass how would it orbit change? [closed]

If a planet becomes lighter, then I believe its orbit will change. For example, the moon is 1/81 of the mass of the earth. So, if the moon disappeared, then the earth-moon system would lose 1/81th of ...
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### Is Earth's moon the only one where a total eclipse of the sun covers the entire sun?

Is Earth's moon the only one where a total eclipse of the sun covers the entire sun? Are any other moons the same size as the sun as viewed from their planet like Earth's moon?
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### How do I calculate moon phase orientation at any Coordinates given all the necessary data?

I'm having a problem for a couple of days where I'm trying to accurately calculate the phase angle of the moon at any given Coordinates (lon,lat).If I know my current Coordinates, Moon and sun ...
91 views

### Moonrise after sunrise but moonset before sunset?

Today (1/24/2020) for Boston MA timeanddate.com lists the following four times: Sunrise 7:05 AM Moonrise 7:06 AM Moonset <...
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### How to compute Ascension / Descension cycle of the Moon

I am struggling to find out an information about how to determine ascending/descending cycle of the Moon. I can find from this source and a bunch of others, that Moon begins to descend when reaches ...
142 views

### What is the cycle for when the maximum amount of the Moon's apparent area is sunlit?

The Moon is defined as full when its ecliptic longitude is 180$^{\circ}$ distant from the Sun's. But what is the cycle for when the maximum proportion of the moon's apparent area is sunlit, and for ...
38 views

### Astronomical events and Celebrations

In the past people celebrated important astronomical events and some of those events are still celebrated in some cultures and traditions. For example: March/September equinox, New Moon, Winter/...
80 views

### Scientific possibility of stationary moons for a writer of fiction

I tried to do some research to find an answer for this question before posting this but didn't find anything that I could sink my teeth into. I was wondering: if it would be possible for a planet to ...
34 views

### Delay of Moon passing a defined meridian each day

On the website Lunar Synodic Curve a nice image of an Moon analemma is shown together with an explantion on the reason why for the different phases of the Moon the images have to be taken with 24h ...
227 views

### Difference in gravity on both sides of the moon

How much (if any) difference in gravity would you feel if you are on the surface of the moon and: standing right 'under' earth (exaclty between the moon and the earth) and on the opposite side of the ...
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### Moon's unusual gravity

We know that the Moon's gravity is about one-sixth that of Earth. Then I recently read that the mass of the Moon is about one-eightieth the mass of Earth. Since gravity depends on the mass of the 2 ...
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### Is there a way to know the time according the moon appearance?

Is it possible know the time according to the moon location? To look at the sky at night and then determine what the time is.
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### Sun and moon's orbit in ecliptic coordinates using skyfield

I am new to using skyfield, is there any doc or help file that can show me on how to get the orbit of Sun and moon in ecliptic coordinate for a particular date and ...
249 views

### Is the Moon not in hydrostatic equilibrium?

Given the recently-announced observations from VLT/SPHERE that 10 Hygiea may be sufficiently round to qualify as the second main-belt dwarf planet, I found myself perusing Wikipedia's Hydrostatic ...
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### how is it possible to see the sun and the moon at the same time? [duplicate]

I once saw the sun and the moon at the same time once. How is this possible? Im from london england U.K and this probably some time in 2017 autumn time at around 6pm any Ideas.
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### Moon Photo from Apollo 12 mission

Can anyone explain why the Moon looks so small and dark in photos taken from cislunar space during the Apollo 12 mission? AS12-53-7887 found at https://www.lpi.usra.edu/resources/apollo/frame/?AS12-53-...
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### Jean Meeus - calculating moon rise, transit and set times - help isolating error in logic

I've been working my way through the Jean Meeus Astronomical Algorithms book for a few weeks, to implement some of the key algorithms for a personal project. This task has been a little more complex ...
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### How do we distinguish old craters from new ones on the Moon?

The following image is the observation made by the Dual Frequency Synthetic Aperture Radar (DF-SAR) onboard the Chandrayaan-2 Orbiter: Due to image size restriction, a lower resolution image is used ...
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### Simulate earth, moon, sun constellation with dates

I would like to simulate the three object distance, specifically the distance of the moon to both, sun and earth for further investigation into tide prediction. What would be a good starting point ...
79 views

### Orbital speed is (vector) sum of tangential and normal speed?

Orbital speed definition in wiki does not state clearly - it is just tangential speed component or square root of squares of normal and tangential speed (full speed vector). When we say that moon ...
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### How to calculate the moon phase angle?

I need to calculate the exact moon phase angle for each our of a day. I have my position in lat and long and a unix timestamp. At the end i would like to be able to caluculate the moon brightness with ...
54 views

### What is the apparent magnitude of the faintest stars visible during a full moon?

Assuming the viewer is far from any light pollution, it is a cloudless night, and humidity is very low. What is the faintest apparent magnitude of stars visible to the naked eye during a full moon (...
42 views

### mm-wavelengths Moon map, scientific case

I would like to test a telescope with a Moon observation. It is a low spectrometer-imager at 110-300 GHz with a resolution of 4 arcmin@150 GHz. Is there any scientific target that concerns the Moon ...
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### Moon changes position

So most nights the Moon usually rises on the right of the sky when I look through the window just like the previous night. But this night the Moon was on the left of the sky rising. Does anyone know ...
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### How many Moon's Topocentric Conjunction occurs per lunar month?

It is clear that only one Moon's Geocentric Conjunction occurs per lunar month, what about the Topocentric Conjunction for a given location? without scale I can imagine many Topocentric Conjunctions ...
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### Is it possible that the shadow of The Moon is a single dot during solar eclipse?

During a solar eclipse The Moon covers The Sun on some places on the Earth. Now the focal point is a bit above the Earth so the shadow area is about 160 miles. In history The Moon was a bit closer to ...
585 views

### Can I see Harvest moon in India?

I just saw articles which say the Harvest moon will be visible in the US. Apart from the US, in which other country can people see it? Can I see it from India?
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### What is the size of the largest asteroid orbiting the Earth, other than the Moon?

It seems odd to me that no other asteroid around the Earth is even close to the size of the Moon. Anyone have any idea about the size and orbit radius of Earth's "second moon" ?
148 views

### What is this object in this photo? [closed]

i took it and i don't know what planet or star is this and also there's our moon
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### 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 ...
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### Did NASA/JPL get “waning” and “waxing” backwards in this video?

The NASA JPL video What's Up: September 2019 Skywatching Tips from NASA says (per both the closed captions and audio): We’re in a several-month period right now when the new Moon falls right around ...
298 views

### Why do I see rainbows around the moon?

Regularly, I see rainbows around the moon. Here is approximately what I see: Right at the edge of the moon, I see a bright blue ring of light. Further out, I see an inner rainbow. This is not as ...
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### How does the Moon's gravity affect Earth's oceans despite Earth's stronger gravitational pull?

Given that Earth has a much stronger gravitational pull than the Moon, how does the Moon have any influence on Earth's oceans?
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### Planets positions (azimuth, altitude) API

I'm looking for a simple API that will allow me to get positions of planets and the moon for a given date, location and time. Does anyone know an API like that? Any suggestions or alternatives would ...
158 views

### If the earth stopped spinning what would happen to the moon

A question was posed at work today, "if the earth stopped spinning what would happen to the moon"? Ignoring any effects on the Earth, what actually happens to the Moon? Does it continue to orbit the ...
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### If the Moon were impacted by a suitably sized meteor, how long would it take to impact the Earth?

An answer to the question of How well would the Moon protect the Earth from a Meteor? mentions as a possibility that the Moon could get knocked into the Earth. What is the smallest change to the ...
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### How well would the Moon protect the Earth from an Asteroid?

Would the Earth fare better if the Moon blocked the meteor, comet, rogue planet, or otherwise rather than a direct impact? At what point would the Moon's debris would be an extinction event? The ...
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### Could Mercury be the creator of Earth's Moon?

Earth's Moon is thought to have been created in a glancing collision with a Mars sized planet. I've just seen an expose on Mercury which claimed Mercury: formed in the region between Earth and ...
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### Satellite in orbit in front of and behind the Moon

Would it be possible to put a satellite into the same orbit as the Moon, but far enough ahead or behind the Moon to remain in place? Has this ever been done in practice?
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### Speed of Moonrise relative to fixed point on ground

Due to the curvature of the earth, and the way the moon interacts with the atmosphere (especially close to the horizon), is there a known function that describes the speed of the moon relative to its ...
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### Where asteroids disappear

Scientists claim that objects left on the Moon can lie hundreds of years in the same condition like astronaut Charles Duke family photo. Why we don't see remains of asteroids inside or around craters? ...
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### Are all satellites thought to be the result of collisions with the planets?

The leading hypothesis for how the Moon was formed was that another object collided with the Earth, throwing off a large lump of matter which formed into the moon. Is this thought to be the case with ...
284 views

### Struggling to understand the phases of the moon

Source Typically this diagram is how the phases of the moon are explained but the issue is this, namely, the phases seen on the right half are not possible. All the phases should appear on the left ...
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### If the moon is losing energy dragging the oceans around, why is it moving away from earth instead of falling like any other satelite would? [duplicate]

If a satellite loses energy it starts to circle lower and finally hits the atmosphere. The moon is moving like an inch a year away from the earth even though it is losing energy pulling the oceans ...
23 views

### Increasing distance of Moon from Earth [duplicate]

I've heard it said that the distance from the Moon to the Earth is increasing. Is it true, and if so what is causing it? (I take it that 'the distance from the Moon to the Earth' is the mean ...
3k views

### Apparent Ring of Craters on the Moon

I saw this picture on the BBC news website. There appears to be a ring of craters in the center of the picture, aligned in an approximate sub vertical orientation. Am I just seeing things or does ...
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### Is the boulder on the peak of Tycho Crater the core of the impactor, or is it a random rock?

There's a strikingly visible boulder sitting right at the top of the peak complex in the center of Tycho Crater on the Moon. Is it just a coincidence that this gigantic, bright rock is sitting dead ...