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Make a Pinhole Projector for Eclipse Viewing

A D.I.Y. pinhole projector for safe viewing of the eclipse takes just a few minutes, and requires some cardboard, a pin and some foil.

 

I'm a sucker for eclipses. Lunar, solar, full, partial. You name it. You just have to be armed and ready.

After all there's nothing better than a celestial event to get people to do things they don't normally do—stay up late, or go outside with anticipation. Or talk to complete strangers because they're sharing something extraordinary.

That's what it was like during the last solar eclipse I saw in 1992, in the middle of the workday. And of course, the advice then was the same as it is this week: Don't look at the sun.

We all came out of San Francisco City Hall, where I worked, with our little makeshift pinhole projectors. We all oohed and ahhhed. And we talked to each other. What are you using? Wow, that's better! Look at that!

When came out, I rejoiced. It's a rare event. You won't see one for years! You gotta go outside!

But I don't recall seeing an eclipse, ever, when I was a child. So with this one, I'm determined to make it a learning event. I told my 6-year-old that we're going to see an eclipse, something I never got to do.

Following the very simple do-it-yourself instructions, I decided to make a simple pinhole projector. There are variations on this. You can make it out of a long, narrow box. We went for no-fuss. It's the principle that matters here:

  1. We cut up a recycled cookie box into two pieces.
  2. We cut a square hole in it (why square? Who knows?)
  3. We covered it with aluminum foil.
  4. We poked a pin through the foil.
  5. And then we took it outside for a test drive.

You can follow along with the pictures. We got all the materials from the stuff in our recycling bags. Your results may vary.

Have fun! That's the point.

What not to do is look at the sun with something that you heard will work, says Professor Andrew Fraknoi, chair of Foothill College's Astronomy Department:

"Sunglasses, exposed film, and smoked glass are NOT OK! If you have access to welder’s supplies (and not many people do), #14 arc-welder’s glass is an excellent filter (but it has to be #14 and not lower numbers). Or you can use special black or aluminized polymer filters/glasses available at many telescope stores or planetaria; make sure you get them from a reliable source."

And if that fails, or looks underwhelming compared to the hoopla over how cool the sun looks, See the list of Bay Area places that are hosting , like the one that Foothill College Astronomy Department chair . National Parks are getting into the fun of it. The Point Reyes National Seashore, which has event throughout the day, is listed among the parks that are "outside the annularity" but will have a good view.

Most of the events are run by astronomical societies and they know what they're doing. They'll have the right filters so that you can look right at the sun, safely.

I'll be at Foothill College observatory just to do that. With my pinhole project in hand—just for back up.

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Just a short thought to get the word out quickly about anything in your neighborhood.
Share something with your neighbors. Write a new post... What's up? Make an announcement, speak your mind, or sell something
Joan J. Strong May 22, 2013 at 11:21 am
Corrections: 1. Straw man attack: nobody is blaming BCS for district-wide growth. Nobody. 2. BCSRead More does not get "half the funding" of LASD. BCS gets about 6500 and LASD gets about 9500. The BCS program for typical children costs about twice as much as the comparable LASD program. BCS is simple an expensive hybrid public/private school, nothing more. 3. Mr. Roode pointed out that there are about 100 or so special ed. students at LASD (I cannot verify this but it seems very low). LASD calls out an annual expense of $7.5 million for special ed. meaning each of these students cost LASD $75,000, not $1,000 as he implied. 4. The law and the courts have ALREADY compelled LASD to give reasonably equivalent facilities and they have. BCS has a lower student/teacher ratio meaning that they have more classrooms for the same number of kids. This is not, legally speaking, LASD's problem. 5. Mr. Roode has yet to explain how the Covington campus could be 16 acres. Further, he continues to spread the fallacy that campuses ACREAGE is even remotely relevant to its student capacity. Campuses are limited by their location and traffic, not how many acres of grass there is in the back. 6. Were it not for BCS, we would have passed a bond in the last election, as the polling shows. BCS litigation has ripped our community apart and has left it with a mountain to climb when it comes to operating in a normal fashion.
L.A. Chung (Editor) May 22, 2013 at 10:37 am
@David R. I think Homestead uses EarthCare Recycling, based on its April 6 E-Waste collection dayRead More publicity (http://bit.ly/10mIV14) : www.earthcarerecycling.com "Recycle FREE your old electronic equipment - working or not! Anything with a plug or PC board inside. Also accepted are non-household batteries, VHS tapes and other media, and scrap metal. Visit www.earthcarerecycling.com for a list of accepted items. "
David R. May 21, 2013 at 10:26 pm
What kind of bins are there? Do you take used CDROMs? How about VHS tapes? Cables and wire?
David R. May 20, 2013 at 01:18 pm
I saw a public report that said most of the discussion related to carpooling and so forth, sinceRead More Blach is separated so much from the rest of the school. You know, things like dropping off both kids at Egan, and then a group of kids headed for Blach share a ride or vice versa. I don't see how any nonparents can really help with that.