# 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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### Implementing the VSOP-2000 Ephemeris

For a project I'm doing, I need to implement the VSOP-2000 ephemeris for the Moon. However, unlike VSOP-87, there is little to no documentation online on how to use the data. For example, here is the ...
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### Moon’s orbit shift

Has our moon’s orbit shifted since its formation? Has there been eclipses on the Earth since last ~4 billion years? In other words, was there a time when Moon's orbit was at an inclination to Earth's ...
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### Simple question about the phases of the Moon

If on March 20 the Moon were located at the position of the sun, how can I determine the phase in September 22, June 22, and December 20? I drew the orbit and calculated by dividing sidereal days to ...
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### Sun, Moon: Relative Distance from Crescent?

This is more a question about the history of astronomy. It recently occurred to me that you can estimate the ratio of earth-moon and earth-sun distance in the following way: We can look at the ...
51 views

### How accurate should sun\moon ephemeris be for calculating eclipses?

I am writing a program to simulate eclipses for about -2000 to 6000. My question is, how accurate does my ephemeris for the sun and moon have to be to get a decent accuracy for eclipses? I currently ...
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### Right Ascension to Zodiac House

At the moment (01-04-2020 09:36) the Moon is situated in Gemini: "The Moon is currently in the constellation of Gemini. The current Right Ascension is 06h 37m 56s and the Declination is +23° 42' 09”."...
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### During an eclipse, how big is the shadow of the moon on the earth?

This picture was taken from the ISS during a solar eclipse. You can see the shadow of the Moon on the surface of the Earth. But how big is this shadow? How many kilometers is its diameter?
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### 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 ...
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### Telescope question [closed]

During the daylight, you hold a ruler in a distance of 60 cm away from your eyes, and you find the size of the Moon to be 0.55 cm (try it yourself!). At night, you use a telescope to observe rock ...
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### Which kinds of astronomical observations most need to avoid the Moon being up?

This comment to Did nobody in the Astronomy community think 12,000 new satellites in LEO might be a problem? links to Phys.org's New ESO study evaluates impact of satellite constellations on ...
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### What are some dark features on (or qualities to) the moon?

I know there are mare, oceani, and lacunae, but anything else that I'm overlooking from lists of lunar features? Does the "dark"/far side have a particular, maybe Latin scientific name (tho it gets ...
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### Calculating the position angle of the moon (the rolling back and forth)

I have been watching the the NASA Moon Phases Video of the year 2020. Pretty much everything makes sense and I know how to calculate it including the moon phases, declination, azimuth, apogee and ...
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### What is the last day a waning moon is visible in daytime (the afternoon)?

From the fourth quarter onward, can we see the moon in the afternoon sky?
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### 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 ...
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### Moon Images from Earth

Is there a resource online of images of the moon (taken from the Earth) suitable for processing with a computer: I.e. taken with the same camera, optics, location, etc, over months/years? Purpose: ...
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### Temporary family member 2020-CD3

So, recently I came to know that this asteroid is orbiting Earth from past 3 years and still it is orbiting. It is kind of a mini Moon to the Earth know to have come from asteroid-belt. Is there ...
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### Why does moon moves to side if I change my position directly into it?

I've setup this scenario on Stellarium where the moon is aligned with East direction. I wanted to see the change of altitude of the moon if I move straight into its direction (time of observation is ...
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### Moon rotation tidal braking

Do we know if the moon had an initial rotation or did it coalesce tidally locked. If it had an initial rotation how long would it take to become tidally locked?
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### Given this report, you can see why people may think the moon landings were fake? [closed]

I was reading today that, in research published in The Astrophysical Journal, molecular oxygen has been discovered in the Markarian 231 galaxy, 561 million light-years from Earth. A light-year, which ...
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### Field rotation and observing the moon

For stars, field rotation can be accounted for with an equatorial mount aligned with the Earth's axis and turning at the correct rate. Since the Moon's orbit is on a different axis then the Earth's ...
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### How to understand the meaning of this International Occultation Timing Association (IOTA) lunar occultation of Mars map?

Earthsky.org's Watch Mars disappear behind the moon on February 18 as well as Moon occults Mars morning of February 18 include the image below and credit it to The International Occultation Timing ...
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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 ...
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### 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 ...
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### 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 ...
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### 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/...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 (...
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### 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 ...