Physics Image projection question

[CM86]

Hopefully I'm not just overlooking something embarrassingly obvious...

How is an image being projected onto the ceiling.
I'll add a terrible diagram to try and help explain it.

I knocked a small hole in a wall and later in the day I noticed a light shining on the ceiling. On closer inspection I could see that it was actually an image of the pool and bricks outside...

So, sunlight is shining down onto the pool and bricks, reflecting back up through the hole and showing an image of the pool and bricks on the ceiling.

I can't work it out. Am I just overlooking something very simple?

 

[Chief]

Camera obscura!

Love those things.

 

[CM86]

Camera obscura!

Love those things.

I'm an idiot.

Thanks for that.

I've just never seen it before, and couldn't work out how this image was being projected, reversed but not flipped.

 

[Chief]

I'm an idiot.

Thanks for that.

I've just never seen it before, and couldn't work out how this image was being projected, reversed but not flipped.

That is an interesting question.

 

[Chief]

I'm looking at Wikipedia - does this shed any light on it? (Ooooo! A pun!)

 

[CM86]

I'm looking at Wikipedia - does this shed any light on it? (Ooooo! A pun!)

View attachment 376213

I couldn't find anything it might be reflecting off.
But you could see the outline of someone walking past. If they went left to right, the silhouette would be right to left. But they were standing the right way up.

I'll have to remove the aircon tomorrow and try and get a picture.
It's only this evening I've tried to work it out, and I've had no luck.