For the past year or so, i’ve been consistently seeing things around me, that I know most people probably don’t even notice or are aware of. I have been seeing projections, images – beams of light, bent by nature. Images on surfaces, all around me (particularly in the afternoon). In fact, just over Christmas, I witnessed something amazing – I saw an upside down, colour image of the front yard of my house, on a piece of paper I was holding (that I was reading)… Just like a “camera obscura”. I find it fascinating how the science of light mixed with optics, works. So here are a couple of really interesting articles that I believe should be shared…
By Julianne Dalcanton
Sometimes rare and wonderful things happen. This weekend, for example, it was sunny in Seattle.
Which allows me to share pictures of one of my all-time favorite Cool-Physics-Around-the-Home tricks:
Anyone who has blinds in their home or office has probably seen something like the pictures above — sunlight streaming through cracks in the blinds, producing a row of spots on the opposite wall. It would be natural to assume that those nice round spots are due to the nice round holes that were poked through your miniblinds at the factory. However, you would be wrong. Those spots are actually pinhole camera images of the Sun!
You observe the same effect, albeit more subtly, when sun comes through tree branches. The network of leaves and branches creates many small holes, each of which produces its own pinhole image of the Sun. These images tend to overlap, making the circles less obvious than with blinds, but you can still see the faint imprints of the circles in places. Sometimes, however, the Sun is not actually round. At sunset when it’s low on the horizon, parts of the Sun can be blocked by trees and buildings. In that case, the pinhole camera images are not round either. I took the picture above shortly before sunset, when the lower half of the Sun was blocked by a neighboring building. You should be able to see that the pinhole images have turned into half circles. (The half-circles are upside down, since a pinhole camera inverts the image.) The effect can get even weirder than the picture above. For example, there’s a large bridge due west from my office window, and sometimes the Sun sets directly behind the bridge. When the Sun is partially eclipsed by the bridge deck, I can even see pinhole images of upside-down trucks driving across the bridge when my blinds are down.
How cool is that!??!! (Ok, I admit, it’s probably not as cool as the Higgs, but it’s a hell of a lot easier to see). I was pretty old by the time I figured this out. The first time I noticed it was during graduate school in the courtyard of a building at the Institute for Advanced Study, during a partial eclipse of the Sun. The moon was blocking about 2/3 of the Sun, making a tidy little cresent. All the tree-dappled sunlight on the ground turned into cresents as well. The effect was spectacular, if not a little odd. I wound up watching the rest of the eclipse on the ground, rather than through my carefuly prepared piece of mylar (i.e., the wrapper off a Poptart). Mmmmmmmm….Poptarts!
If you went outdoors to observe the solar eclipse yesterday, you might have noticed that the shadows cast by trees had suddenly become quite strange. The tiny gaps between leaves act as pinhole lenses, projecting crescent shaped images of the eclipsed sun onto the world below.
Here are a couple videos showing the same thing:
P.S. The Frame has an incredible gallery of eclipse photos that you’ve got to check out.
Image credit: Eclipse shadows by bob, annular eclipse shadows by just sof, Eclipse shadows by ChathuraW, The Eclipse Tree, Basildon. by Picture Esk, and P1040627.1 by Cantavestrella