# Selenelion Eclipses

#### Johnny Orbital

##### New Member
Hey guys, hey Mick

first post on the forum, I hope everyone's doing well

So, I understand that the selenelion lunar eclipse is caused by atmospheric refraction..

https://en.wikipedia.org/wiki/Lunar_eclipse#Selenelion
I also understand that the shadow comes top down due to the refraction causing the moon to appear higher than it actually is, coupled with the rotation of the earth.. so the moon is effectively moving upwards into the earth's shadow, but the rotation of the earth makes it appear as though its moving downwards from our perspective on earth

I get it

I'm just struggling to find sources explaining the direction of the shadow in more detail than I can muster up

can anyone please direct me to a source which actually explains the rotation aspect of the shadow

or if Mick could do a short video on it, that'd be a great help when these flat earthers struggle to understand.. which for once, is actually understandable, many of us globers struggle to explain it too

I get it, but I like to be able to cite sources too

thanks guys
(if you're interested, go watch Mick's interview with me on his YouTube channel)

Last edited:

#### Mick West

Staff member
I'm just struggling to find sources explaining the direction of the shadow in more detail than I can muster up
There's nothing particularly special about the direction of the shadow motion for a selenelion lunar eclipse. It's the same basic geometry for one that happens during the hours of darkness, just with some added refraction. So really the question should be how to explain the direction of the Earth's shadow motion in ANY eclipse. Still, we could focus on the example you give, of an eclipse occurring at moonrise (just as the sun is setting)

It is, as you said, understandably difficult to understand. The simple way I picture it myself is to imagine the shadow of the Earth as a dark disk cast on the celestial sphere (the imaginary sphere, very far away that the stars move in).

Try to ignore the rotation of the Earth for now.

The moon is creeping slowly across the celestial sphere at a rate of one full 360° every 28 days (about 13° per day). The Earth's shadow is also moving across the sphere, but much slower, once every 365.25 days, or about 1° per day. So the Moon is moving at 13x the speed of the Earth's shadow. We can start to imagine it simplified as that shadow not moving, being fixed in the celestial sphere (the stars) and the moon simply going through it.

What would REALLY be helpful would be a video where the celestial sphere (the stars) was fixed, and we see the moon travel across it, through the earth's shadow. Something like this.

The problem is that it's difficult to make such videos, and so videos of eclipse tend to with be fixed on the moon, or fixed on the earth itself. And in both cases we can't see stars.

When fixed on the moon, it looks like the Earth's shadow is moving across the sky. What we want is the Earth's shadow fixed, like this:

Then you've got to see that in the context of the rotating celestial sphere

#### Attachments

• Untitled Project-1.mov
1.8 MB · Views: 42

#### Johnny Orbital

##### New Member
Thanks Mick, it's just I've got a guy giving it the 'the shadow shouldn't start at the top of the moon' line.. and it's actually the sunrise selenelion, not the moonrise one I'm trying to explain to him

that equatorial mount absolutely mesmerises me every time!

I know we discussed the selenelion on the video we did, and I feel like I AM explaining it perfectly to him.. he also seems to have some basic knowledge of physics which leads me to believe he's just being difficult

I might just try making a video for him, a ball in each hand, move the moon ball up slowly, rotate the earth ball slowly and show him that even though the moon is moving relatively upwards into the earth's shadow, that due to the rotation of the earth, the moon can appear to be moving downwards relative to our perspective from the earth

it's so much easier being a flat earther; FAKE!! and onto the next lol

I hope I made sense here

##### Member
Thanks Mick, it's just I've got a guy giving it the 'the shadow shouldn't start at the top of the moon' line.. and it's actually the sunrise selenelion, not the moonrise one I'm trying to explain to him

we have an illustration here showing how such a lunar eclipse can occur, even if the shadow is eclipsing the top portion of the moon, and still end up with plenty of wiggle room in the geometry.

Replies
3
Views
2K
Replies
19
Views
3K
Replies
4
Views
3K
Related Articles