Thursday, June 14, 2012
Venus Transit (or Not)
Last Monday, Lea needed to take Gillian to the pediatrician in the afternoon, so I used some of my sweet new "Family Medical Time Off" and came home a couple hours early to stay home with Colin. You may remember that last Tuesday (June 5th) was the Transit of Venus. Given that the kids are pretty space crazy at the moment (they must have watched Team Umizoomi: Door Mouse in Space about 100 times), I thought that maybe we should build a Pinhole Projector to try to watch the transit.Colin and I set about our task with much enthusiasm. We first tried to build a relatively simple projector consisting of a piece of mat board with a foil aperture. We took this outside, and with Monday being relatively sunny, hoped for the best. It seems, however, that we couldn't really get a dark enough shadow to allow us to see the image from the projector, so we added a black fabric hood (Mark Ia, seen here being snuggled by Weasel):Even with the fabric hood, this was kind of a bust in that the hood wasn't long enough to all you to get the front of the projector far enough away from the ground to make a decent sized image. Thus, on to Mark II.After reading a bit more about the throw lengths needed for a given image size, and wanting to get a somewhat darker viewing area, Colin and I set about building a new projector from an old wrapping paper tube. Alas, we only had one spool of wrapping paper that was close enough to empty that we could in good conscience steal the tube, and that only got us about three feet of throw. Being resourceful gents, however, we remembered that there was a freezer pizza box waiting to be taken to the garbage so we grabbed that, and managed to add about two more feet of throw to our projector. Behold the Mark II:This version has a relatively good length (though it still only produces an image of the sun that about half of an inch in diameter) and has an enclosed bottom so its darker for better viewing (apologies for the blurry camera phone pic):It's not immune from problems, however. Because the tube is so narrow, it's actually very difficult to find the sun with this projector - you really have to have good aim to get the sun onto the target surface. Also the joints between the sections aren't really very strong, so you have to treat it gently.Anyway, Colin and I managed to get this put together on Monday afternoon, and I believe that he was pretty excited that we were going to see another planet. Then came Tuesday...Clouds - thick, heavy clouds - all day long. Not a chance of viewing the transit (there was like thirty seconds at around 6:20 when the sun poked out through the clouds - but I couldn't manage to find the sun with the projector in that amount of time). Thus we were forced to see much more impressive pictures on the iPad, though I don't think it quite lived up to Colin's expectations (though, I'm pretty sure he would have actually been more disappointed with the projector as Venus would have been like a pin prick on the half-inch face of the sun).At any rate, it was a fun little project in building our own scientific instruments, so hopefully that made an impression... and we can always pretend that it produced images like this.