Space and Physics
PUBLISHED
26
A man has turned to Facebook for answers after noticing that his neighbor's house was projected upside-down onto his bedroom wall. It's not a sight you expect to wake up to – for one, neighbors' houses are generally not upside-down, and rarely on the inside of your own house. So, sharing photos of the incident, Stefan Lægaard Andersen appealed for an explanation.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content."I'm sure that some of you fine gentlemen and/or gentlewomen know the answer to this ginormous mystery, that has my head spinning," Andersen wrote in the post. "Last night, as I was tucking my daughter into bed in our new house, this mirror image of the neighbours house showed up as a projection of sorts on our bedroom wall. I have absolutely no idea, how this happened, but I am hoping some of you can help understand this mystery."
Further confusing the situation, and offering the explanation, was the fact that the man's bedroom window was covered at the time. Although stopping most of the light getting through, people were quick to point out the explanation.
"So, having the window blocked off like that effectively makes it a pinhole camera, or camera obscura," commenter John Tougas explained. "The light reflecting off the building comes through the window, which is acting like a lens, and projects onto the wall. Very early experiments in photography used similar arrangements."
Pinhole camera effects are fairly commonplace, though not usually as spectacular as the one witnessed by Andersen and his daughter. Gaps in the light between the leaves of trees can create the same effect. On ordinary days, when the sun is out, you will see projections in the shape of the sun on the floor. This can be particularly pleasing during an eclipse.
A similar effect using "pinhead mirrors" means you can even turn disco balls into an eclipse-viewer. Which is pretty neat.
