Solar Observation Device

You thought it was going to be a satellite or some large piece of equipment in miniature form didn't you?  These are home made camera obscuras (cameras obscura? camera obscurae?) for the kids and myself to watch the solar eclipse tonight without burning out our retinas. The idea surfaced from a childhood memory when I made one from instructions from an astronomy magazine for kids. I was probably somewhere around 10 years old or so. (They say something is the first to go as you age, but I'll be darned if I can remember what it was.) With age though has come some improvements on the original. First, the interior was spray painted flat black. Blank paper is more readily available than when I was a kid. (I used regular notebook paper in the original) Light "leaks" have been more aggressively addressed than the original. And finally the viewing hole was made smaller to reduce the amount of light infiltrating. These work pretty well. I get about a 1/4" disk when viewing the sun unobstructed, and standing under a tree I can see a faint image of the branches over the projection surface (white card stock).

I used a shoe box, a bunch of duct tape and electrical tape, black spray paint, white cardstock (regular paper works as well), and aluminum foil. Use the tape to cover spots where light will enter the box. Paint the interior black. Cut the cardstock or paper to fit on the inside of one end of the box and tape into place. cut a small opening on the opposite end and tape the foil over the opening, making sure the side are completely covered and most importantly that the foil is taught. Using a small sewing needle, poke a tiny pinprick of a hole in the foil. Put the lid back on and tape around it to block the light. Cut a small hole in the side so you can see the paper. Go outside and looking into the viewing hole point the foil-end at the Sun and with small movements move the box so you see a bright disk on your paper...that's the reversed and inverted image of the Sun. During the eclipse we'll be able to see the Moon cross the disk.

I still think I'm going to have to tell them not to look at the Sun.

How Stuff Works

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