I understand there are normal phases where the moon is partially covered by the Earth’s shadow, how can it be completely covered one night and full the nights before and after? What happens during an eclipse where the moon can go through all the phases in a few hours, and then go back to full tonight and normal decreasing/increasing phases each night?
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>I understand there are normal phases where the moon is partially covered by the Earth’s shadow, how can it be completely covered one night and full the nights before and after? What happens during an eclipse where the moon can go through all the phases in a few hours, and then go back to full tonight and normal decreasing/increasing phases each night?
The phases of the moon have nothing to do with Earth’s shadow.
Shadows of astronomic objects on other astronomic objects are solely eclipse-business. Parts of the moon not being lit up by the sun during the phase cycle are **the moon’s own shadow**. The sun can only illuminate one side of it, after all. Your viewing angle determines how much of its illuminated side you see.
An eclipse will always happen at the full moon, because that’s when the sun and moon are on opposite sides of the earth, meaning that we see the fully illuminated side (full moon). Similarly a solar eclipse (moon passing between sun and earth) will always happen at anew moon.
The only reason lunar eclipses don’t happen at every full moon is that earth’s shadow is not that big, so the angles have to be just right in order for the moon to pass through it.
Edit: I should add that normal moon phases have nothing to do with earth’s shadow, but with the relative angle of the earth-moon-sun system, which changes how much of the illuminated side of the moon we can see. Eclipses are the only time when our shadow falls on the moon.
There are usually around three consecutive nights where the moon looks full. It’s just because it’s hard to see the difference between completely full and close to full. The sun (being very large) lights a little more than half the moon and one person (from a single point of view) sees a little less than half of the moon.
Easiest way to explain
Is you need to go and look for the moon every day and night for 28 days and keep a diary.
A full moon won’t be seen during the day (full moon at night no moon during the day) and during a new moon,
No moon during the night, but you will see part of the moon during the day (and when that path crosses the sun you get a solar eclipse)
As the moon moves between phases you will see more or less of the moon each day/night.
To make it more interesting, the moon wobbles on its orbit, so sometimes it’s more north or south of the “solar plane” which is why you don’t get a solar or Luna eclipse every month (and sometimes years apart)
>I understand there are normal phases where the moon is partially covered by the Earth’s shadow
That’s incorrect. The moon’s normal phases are not due to Earth’s shadow. The moon’s phases happen because the sun illuminates half of the moon and how much of that illuminated half we see depends on which side of it we’re on. [Here’s a blog post that explains it with a diagram](https://alex.strinka.net/blog/why-does-the-moon-have-phases.html).
A lunar eclipse can *only* happen during a full moon, because that’s when the Earth is directly between the moon and the sun. [Here’s another blog post that explains that.](https://alex.strinka.net/blog/eclipses.html)
The Full Moon is the Moon being front-lit by the Sun, “over Earth’s shoulder”. The Quarter Moon is side-lit by the Sun, “from the left/right”. The New Moon is the Moon being between us and the Sun, so that it’s visible in the daytime sky but lit “from behind” at night.
The only time the Earth can fully eclipse the Moon is when ~~it’s~~ *Earth is* between the Moon and Sun, which is the same condition for a Full Moon. On Monday, the Sun lit the Moon over Earth’s right shoulder. For a brief while Tuesday, the Earth’s head threw a shadow over the Moon (the eclipse). Then Wednesday, the Sun lit the Moon over Earth’s left shoulder. Last month and next month and most months in general, the Earth isn’t exactly as “high” as it needs to be to throw that shadow during a Full Moon. Remember the Sun is huge and very far away, and the Solar System is not perfectly flat and neat.
The moon’s phases are its own shadow… Not the Earth’s. When the moon is up in day time hold a ball up online with it from your view, the ball and the moon will have the same phase.
An eclipse occurs when the earth is between the moon and sun and so from earth it’ll be fully illuminated
The scale of things might be wrong in your mind. The shadow of earth is tiny compared to the distance of the orbit of the moon.
[https://www.youtube.com/watch?v=kgY60MTURp0](https://www.youtube.com/watch?v=kgY60MTURp0)
this video is slightly more to scale, though not entirely accurate either.
another earth moon scale video
[https://www.youtube.com/watch?v=Bz9D6xba9Og](https://www.youtube.com/watch?v=Bz9D6xba9Og)
another solar system scale website. Scroll to the right a bit and then icons will appear toward the top of the screen, lets you jump to the earth and moon.
[https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html](https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.jtml)
EDIT:
I may have misunderstood the problem at question here and maybe this video can shed some light on how the phases of the moon are due to its location in orbit around the earth, which is separate than the psuedo phases you see as it passes into earths shadow.
[https://www.youtube.com/watch?v=AQ5vty8f9Xc](https://www.youtube.com/watch?v=AQ5vty8f9Xc)
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