On August 21st, 2017 a large portion of the Continental US will experience a total solar eclipse. Much of the rest of the continental US will experience at at least a partial eclipse: Philadelphia will have about 78% totality, NYC 75%, Washington DC 84%, Chicacgo 88%, Los Angeles 70%, Seattle 93%, etc.
Naturally, many of you will want to view this eclipse as it happens. This is great and it can be very fun to watch. But here’s the thing:
IT IS VERY DANGEROUS TO STARE AT THE SUN!
Let’s let Linus explain:
Or the some old dialogue from Dana Carvey’s ‘Grumpy Old Man’ character from Saturday Night Live:
“In my day, there was only one show in town — it was called “Stare at the sun!” … That’s right! You’d sit in the middle of an open field and stare up at the sun till your eyeballs burst into flames! And you thought, “Oh, no! Maybe I shouldn’t’ve stared directly into the burning sun with my eyes wide open.” But it was too late! Your head was on fire and people were roastin’ chickens over it. … And that’s the way it was and we liked it! “
Nevertheless we have encountered more than a few people who are surprised that they can’t just use sunglass to view the eclipse.
Well, you can.
But you really, really, really shouldn’t!
As you may already realize, starting at the sun is already painful. Using basic sunglasses or other non-solar films may cut down on the visible light but not on the harmful UV rays that can do serious damage to your eyes.
Seriously, just don’t stare at the sun without proper equipment.
Now, keep in mind that the Peanuts comic dates from 1963 and this was before certain solar filter technologies became available to the general public. Things have changed quite a bit since then and your options for viewing the eclipse have increased a lot. Each one will have advantages and disadvantages. Let’s take a look.
Telescope with a Solar Filter
You might think to yourself “This is perfect! I have a telescope so I can just get a solar filter for it and I’ll be all set!”
Well, yes and no. If you Fast (short tube telescope with a short focal length) Telescope a solar filter will be good if you can get the magnification low enough to fit the entire sun in the field of view. Otherwise the magnification will probaly mean you are only have a part of the sun in the field of view at any time, and you really need to see the entire disc of the sun to get the full experience. Generally speaking you will want to keep the power well below 100x and the lower the better. Remember you are trying to get the whole sun, not just details of sunspots!
One issue of using a telescope is aiming and tracking. In an upcoming blog post will we discuss aiming a telescope at the sun. This can actually be tricky as you cannot use the finder scope to aim.
BTW, we assume you are using a proper aperture solar filter from a reputable company. If you have one of those solar filters that thread onto the telescope’s eyepiece, DO NOT USE IT. They are dangerous and can result in eye damage.
If you don’t have a solar filter for yor telescope (and they may get very hard to get as the eclipse time gets closer). You might consider doing projection of the solar disc. We did an entire blog post on how to do this properly, and while it can be tricky, it does have the advantage of letting multiple people see it happen.
Essentially, instead of looking through the telescope, you use the lens(es) & mirror to project an image onto a bright surface:
Viewing the Eclipse without a Telescope:
If you don’t have a telescope you can still view the eclipse. Consider these methods:
The most economical method is to use some cardboard and other low-cost materials to make a pinhole projection system. There are several sites describing how to do this better than we can, so here is NASA’s page on projections
There are several other desings f Pinhole Camera projection and none of them involve much expense, so consider which deisng might work for you and try to build a few to see which works best for your viewing needs.
Eclipse shades are low-cost cardboard glasses, not too different from the cardboard ‘3D’ glasses you would get at some old movie theaters, but instead of colored filter lenses they have proper solar filter film in place! This will let you look directly at the sun during the eclipse without harming your eyesThe only downside to eclipse shades is that they have no magnification, but for an eclipse this is not such a big deal. If you were viewing a transit of Mercury or Venus, or view sunspots then they wouldn’t be very useful.
Be warned, however, that some unscrupulous vendors have been selling defective eclipse shades. This is not an area where you want to risk a few pennies. These are your eyes we are talking about! Be wary if your eclipse glasses are not from American Paper Optics, Rainbow Symphony, Thousand Oaks Optical, and TSE 17. If you have an older pair of eclipse shades (3 years or more) or if there are any scratches or holes in the lenses, replace them.
Enjoy the Eclipse!
Want to buy Eclipse Shades?