23

Note: this answer was posted under duress; though I mentioned in a comment under the question that I was composing an answer, several users have decided to close the question out from under me. Therefore I've put this together a little hastily. It's late here and I'll come back in the morning to address any questions or requests for clarification, and ...


15

Think of it like this: Each hour after New Moon, the Moon is moving away from the Sun. Depending on the position of the Sun, Moon, and observer, it is unlikely to be visible until at least 15 hours after New Moon, and in some cases not until 24 hours after New Moon. Someone will be the first to see the thin crescent after the New Moon. This occurs when the ...


13

The dark parts of the Moon are partially illuminated by "Earthshine". That is sunlight which is reflected from Earth to the Moon. Just like the ground on Earth is lit up a bit by the Moon at night, so is the ground on the Moon lit up a bit by the Earth in the lunar night. And even more so because Earth is much larger in the lunar sky, than is the ...


12

The Earth-Moon System is a system where the moon is tidally locked to the planet, but the planet is not tidally locked to the moon. Earth has a 24 hour day, whereas the Moon has a 29.5 Earth day long day. It takes the Moon 29.5 Earth days to orbit around the Earth once as well, which means the Moon is tidally locked in a 1:1 ratio. This means that if you ...


10

The duration of one lunation (the period between one new moon to the next one) isn't neither constant as the Moon rotates around the Earth and it around the Sun (changes between 29.272 and 29.833 days due to the perturbing effects of the Sun's gravity on the Moon's eccentric orbit), nor integer divisible by 24 hours or one Earth's rotation around its axis. ...


9

A better diagram is something like this: Day 0. The Moon is aligned with the Sun (New Moon) and some star X behind the Sun (of course :-), as shown by the arrow at 1. (Neither the Sun nor the star X are shown in the figure.) Day 27.32. One sidereal month after figure 1. The Moon has travelled through 360 degrees orbiting around the Earth. (During that ...


8

You can generally see the unlit side of the moon when a considerable amount of sunlight is reflected off the earth. This reflected sunlight illuminates the unlit side of the moon. This is referred to as earthshine, and a decent explanation can be found at timeanddate.com. I seem to recall reading somewhere (but now can't find a reference) that it is more ...


7

The visibility of a narrow crescent moon depends not only on the width of the crescent, but also on the difference between the moon's and sun's altitudes relative to the local horizon. The greater this difference, the darker the sky near the moon can be before it sets. Estimated moon visibility maps for 2018-06-14 by the UK Nautical Almanac Office and R H ...


7

I think they did make a mistake. The moon waxes after a new moon and wanes before a new moon. To wax means to grow bigger or stronger (and is cognate with "waist"!). To wane means to become smaller or weaker (cognate with "waste" and "vaccum"). The moon that sets shortly after sunset in the evening is a waxing moon. The moon that rises shortly before ...


7

JPL HORIZONS can do that. With settings like these: Ephemeris Type : OBSERVER Target Body : Moon [Luna] [301] Observer Location : Geocentric [500] Time Span : Start=2019-09-12, Stop=2019-09-19, Step=1 d Table Settings : QUANTITIES=10,23,24 it returns results like these: Date__(UT)__HR:MN Illu% S-O-T /r S-T-O *************************...


5

It's poetically called The Old Moon in the New Moon's Arms. Project Earthshine used measurements of the brightness of the non-sunlit portion of the moon to accurately determine earth's albedo: A global and absolutely calibrated albedo can be determined by measuring the amount of sunlight reflected from the Earth and, in turn, back to the Earth from the ...


5

The dull red color has been due to atmospheric causes, like the reddish sun close to sunset. There hasn't been an astronomical reason for the reddish color. A few days after New Moon moonset occurs short after sunset, so you won't see the Moon high over the horizon at those evenings. With each day the Moon is a little higher above the horizon after sunset. ...


5

If you take a line from the middle of the terminator, but at 90 degrees to the termination, it more or less points towards the sun. Now consider the moon at first quarter: as the moon rises, the sun is due south, so imagine a line from the moon to the sun, and the terminator will be at 90 degrees to this, so pointing from bottom right to top left. At mid-...


5

The moon phase is corresponding to the position of the moon round the earth. The peak of full moon is the same time. At this time, one side of the world that can see the peak of full moon and another side not. As the phase change is much slower than earth rotation, another side of the world can see near full moon at the moon-set or at the moon-rise, a few ...


5

As others have said, the full moon (date and time) is set by when the center of the Moon passes over or under a line that passes from the center of the sun through the center of the Earth. That gives the full moon a precise time, to the minute, that's the same everywhere on earth, provided you adjust for timezone. The "over or under" is important, ...


5

Here are some answers to your various comments and questions: you can estimate a direction of south True, but it would be a very rough approximation at best. In order for it to be accurate, the bright limb of the Moon would need to face either due east or west on the celestial sphere. (In astronomy terminology, the position angle of the bright limb would ...


5

tl;dr: An observer on the "Moon side" would see only half the phases during the fortnight-long night: from waxing half-moon to waning half-moon. They would also see the Moon during the day (early morning, late afternoon), as we currently can, but they would never see the New Moon or crescent moons at night since these would be only visible during the day. ...


4

As the older answers stated, Earthshine is what you're seeing. Compared to the Moon as seen from Earth, Earth as seen from the Moon has almost four times the apparent diameter, and close to 14 times the apparent surface area. If Earth's reflectivity were the same as the Moon's, that would make Earthlight on the Moon 14 times brighter than moonlight on the ...


4

The moon's phase isn't easy to calculate accurately. Fortunately, the 4 main phases (new moon, first quarter, full moon, last quarter) are a bit more stable than the intermediate phases. Good main phase algorithms use a dozen or so sine calculations for the new or full moon, and a similar number for the first or last quarter. Those two algorithms you linked ...


4

Other than it being a Full Moon and the Moon is high in the sky, there is nothing unusual going on.


4

I can't give a definitive answer, but food for thought. The Moon orbits on about a 5 degree inclination to the Earth's orbit around the sun. Because the full Moon happens when the Moon and Sun are on opposite sides of the Earth, the Moon is most directly opposite the Sun near the Spring and fall equinox. That makes the Harvest Moon (full moon closest ...


4

As noted in a comment, you should imagine the picture is looking down on the Earth, and remember that the actual moon is much further from the Earth, relative to their sizes. Imagine a person standing on the left side of the Earth (in the diagram). The time would be midnight for them. They could see the moon when it is full, and they could see the moon when ...


4

The text directly underneath the diagram from the original source says Diagram Explanation The illustration may look a little complex at first, but it's easy to explain. Sunlight is shown coming in from the right. The earth, of course, is at the center of the diagram. The moon is shown at 8 key stages during its revolution around the earth. The moon phase ...


3

As months are not of fixed length it is only possible to calculate an average. From Wikipedia: The average frequency of a blue moon can be calculated as follows. It is the period of time it would take for an extra synodic orbit of the moon to occur in a year. Given that a year is approximately 365.2425 days and a synodic orbit is 29.5309 days, then there ...


3

The motion of the moon is known with great accuracy, and so the exact moment of a new moon (the moment that the sun and moon have the same longitude in the sky) can be calculated with great accuracy for tens of thousands of years into the future. This is the astronomical meaning of New moon, and the only one which is relevant here. The uncertainty is due to ...


3

The answer depends on what you mean with "precisely". The ELP theory seems to have an accuracy of ~10-6° in longitude over a century, which comes down to about a millisecond for phases.


3

A relatively simple way to understand why the moon axis seems to rotate is to observe that the stars do the same thing. Watch over several hours as Cassiopeia - located near the North Star moves and you'll notice the orientation changes. Cassiopeia, for example, is shaped like a "W" when lowest in the sky, a "3" as it rises, an "M" as it reaches its highest ...


3

From the US Naval Observatory: Crescent Moon Visibility: Naked-eye sightings as early as 15.5 hours after New Moon have been reliably reported while observers with telescopes have made reliable reports as early as 12.1 hours after New Moon. USNO is usually a very reliable site for info like this.


3

There is an accurate depiction of the moon phase and shape in Stellarium (see below) that you might find useful. You can select your observing location and time anywhere on Earth (or another planet if you so wish). Then you can just search for the moon in the search window (if you cant spot it in the sky), and you have a real representation of how the moon ...


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