# Last night there was a lunar eclipse but the night before and tonight it is almost a full moon, how does that work?

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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?

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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.

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.

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.

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)