Experiment #4: The DIY Solar Eclipse Pinhole Projector

Back in my University days, I took an astronomy class that strengthened my already strong fascination with the workings of the universe.

I remember covering solar eclipses, and looking at the dates of the ones set to cross the US, and noting one that would be in Florida in the 2040s, conveniently where my parents live (and my family has lived for generations) and where I was certain I would be headed in the 2040s no matter where I was living to get a chance to experience a total solar eclipse myself. I've been dreaming of seeing one.

I failed to note that others might occur near me earlier than the 2040s, leading me to miss the fact that one would occur in 2017.

Silly eighteen year-old me, messing things up for older me. Oh well.

Fast forward to August 2017, and I am waiting for a pair of eclipse viewing glasses to hopefully make an appearance on my doorstep before the 21st. I am not fortunate enough to be able to make the trip to anywhere on the path of totality.  If the glasses don't make it, I'll save them for the next one. In the mean time, though, I do want to make sure I have some way to view the partial eclipse in my area, so I am setting about my next experiment: making and testing several types of pinhole projectors.

Here goes Experiment #4, the most scientific of my experiments so far. Please excuse any non-scientific practices, as I am just an English teacher who loves science.

Projector Options

Option 1: The Colander Method 

For real? Supposedly yes. According to Neil deGrasse Tyson and the witty writer of this article, you can use a colander (the type with holes rather than mesh) as a pinhole projector. I appreciate the description of the colander as a "many-pin-holed-kitchen-camera." This assembly takes no time at all, although I still need something to project the image on (white printer paper or poster board will do the trick, I think). I happen to have three different sizes of colanders, including a cute little portable one that should be just what I need to try this out.

Option 2: The Cereal Box Method

My husband's box of frosted wheat cereal was the sacrifice here. The cereal is now without a box.  I got this idea one from the same site I got the colander method from, and I am debating which one will look more unusual when I go out in public to use it.

All you do is cut two holes in the top of a cereal box, tape foil over one hole and make a pinhole in it. I actually used a sewing pin. You look through the other hole.

I believe a shoe box would probably work as well if you have one.

Update: For the actual solar eclipse, for using this for the sun, I've seen that you have potentially to take a note from the paper method and use white paper in the bottom of the cereal box. Consider making the whole a little wider too, if necessary.

Option 3: The Paper Method

This one showed up a few places. All you need is two sheets of paper or white cardboard or poster board. Poke a pinhole in one, and project the image onto the other. I just opened the paper drawer on my printer and took out two sheets.

Testing:

I grabbed my phone, first, and was successfully able to project a round image of the light with each of these projectors. I tried next to use an old flashlight we kept for hurricanes. This flashlight did not work well with the projectors. However, when I dug out an LCD flashlight that was one of those free trinkets companies give away at conferences and job fairs, I had success in testing. This flashlight was, I believe, a good test light source because it has many separate bulbs rather than one large bulb.

When I shone this flashlight's beam through my projectors, I as able to see each of the individual light bulb's light in a distinct image with each projector. There was a clear winning projector though in terms of clarity of the image, and allowed me to see that my pinhole projectors are able to distinguish between lit an unlit areas in the light source.

Here are my results. I have included pictures of each projector's projection, and have not altered the pictures of the projections in any way other than cropping them, so that you may have a realistic idea of what they look like.

My oh so sophisticated projector mount:
Two dining chairs

3rd place: The Paper Projector: 

While certainly a contender in terms of price and ease of building, this was the weakest projector. It did cast a clear image; however, in even just the light of my house it was almost impossible to see the image projected, it was so faint. Note that you must have the paper to project the image on to if you use this method. If I took away that white paper that I projected the image on to, you could not see the projected image at all.

The image of the distinct light bulbs is visible,
but very faint

2nd Place: The Colander Projector

This one involved no labor at all, and did cast a clear image. The only concern I have is how clear that image will be outside in the real sun. It would probably work just fine, especially since it shouldn't be as bright out as usual.

The projection is easily visible, but can be
a bit blurry

1st Place: The Ugly Cereal Box Projector 

This projector made a clear image, and solved the problem of light making the image faint by casting the projecting into a dark box. It was the most labor intensive of the projectors, but it still only took about 5 minutes to make.

Certainly the most visible and sharp image

I'll be heading out with probably all of these options on August 21st to see what I can see. Hopefully I will also have my solar eclipse observing glasses and a sunny day!