With the eclipse less than a week away, more and more people are getting excited and beginning to plan on viewing this cool astronomical event.
If you've not purchased solar-safe glasses -- eyeglass frames (usually cardboard) with a film that filters out more than 99 percent of sunlight, which makes it safe to look at the sun -- you may be too late. It may well be past the deadline for online orders, and local stores may have exhausted their supply.
I've heard from people who plan to stack up sunglasses, under the misguided idea that multiple sunglasses will render the sun safe to see: IT WILL NOT.
Some words of wisdom:
1) Never ever NEVER EVER EVER NEVER look directly at the sun without proper filters. A couple pair of sunglasses ARE NOT proper solar filters.
2) Not all solar-safe glasses are made the same. Read this story from space.com: bit.ly/2uqatZB.
3) Do NOT use the solar-safe glasses with binoculars or a telescope. If you do you WILL BURN YOUR EYES OUT. Here's a video from Springdale-based Explore Scientific showing what will happen: bit.ly/2uHuLNy.
I don't want to discourage people from viewing; rather, I want people to be able to see for the rest of their life.
If you do not have solar-safe glasses and can't find any, and don't know of anyone with a pair -- remember, the eclipse goes on for hours, so a single pair of glasses can provide views to lots of your friends, neighbors, co-workers -- there are a couple of avenues you can pursue.
A solar projector is an easy DIY project: All you need is a cardboard box with a lid, some tinfoil, a piece of white paper, some tape, a needle, and a knife. Here's an online tutorial on how to do it: bit.ly/2wJ2Q18. The longer the box, the larger the image; however, as the image gets larger, the brightness of the projected image gets dimmer.
As I wrote a couple weeks ago, maybe the easiest way to watch the eclipse is to find a tree and look down -- and it's best if the tree's shadow is on concrete. All that dappled light under the tree is actually the sun shining through gaps in the leaves -- meaning that the light is actually images of the sun projected on the ground. As the eclipse progresses, the moon will take a progressive larger bite out of the sun, the image of which will be visible on the ground. The viewing can be enhanced by placing a piece of white paper on the ground.
Another method of watching is using binoculars to project and image on a piece of paper. DO NOT LOOK AT THE SUN WITH THE BINOCULARS. With the big end pointed at the sun, place a piece of paper under the eyepieces. With a little adjustment of focus, angle, and distance of the paper, the binoculars will project an image of the sun onto the paper. Oh, and do NOT use the binoculars to look at the sun.
The eclipse is going to happen on a very predictable schedule.
If you happen to be standing in The Weekly Vista parking lot in Town Center West in , the eclipse starts at 11:42 a.m., reaches maximum at 1:12 p.m., and ends at 2:40 p.m. (In my July 19 column I failed to correctly subtract from Universal Standard Time, and reported the end was at 3:40 p.m.)
At 1:12 a.m., 92 percent of the sun will be blocked by the moon. While that sounds like a lot, there's still enough sunlight to immediately damage vision. I cannot repeat this enough: DO NOT LOOK DIRECTLY AT THE SUN.
One question I got asked last week was why the shadow moves from west to east, when the moon rises in the east. Took me a minute to figure out the answer.
Because Earth moves east as it rotates on its axis, the sun appears to rise in the east and set in the west.
The moon, when it's full, does rise in the east. But the moon revolves around the Earth going from west to east. When the moon is a new moon, it's in the western sky with the sun, and each night for the next 14 days it moves east until it's a full moon.
Think of the Earth as a fixed point (even though it's not). The sun is moving west, the moon is moving east. When the three line up, the shadow of the moon is cast onto Earth and it follows the moon as it moves east.
The moon always casts a shadow from the sun somewhere, right? Right. It just so happens that during an eclipse that shadow is cast on Earth.
From a high vantage point such as a mountain with a clear view to the west, or from an airplane or space, the shadow can be seen racing along Earth's surface. It's a giant round black spot. And it's moving fast. In St. Joseph, Mo., where I'll be viewing, the speed is 1,499 mph. South of St. Louis, the shadow is moving at 1,459 mph. In Casper, Who., it's racing along at 1,713 mph. The speed changes because of the Earth's shape. It's fastest on the ends. At the extreme eastern end, where the eclipse ends in the Atlantic Ocean south Cape Verde Islands, the speed is a paltry 74,851 mph. How can I call that speed paltry? Because at the extreme western end, where the eclipse begins halfway between Midway Atoll and the Aleutian Islands, the shadow is moving at 102,791 mph.
I must credit the way-cool website created by Xavier Jubier (shortened link bit.ly/2uVsBvb), which is where I found the data cited here.
For most of us, this eclipse can serve as a practice run for the eclipse on April 8, 2024, when Town Center will see more than 97 percent of the sun covered by the moon. In 2024, the path of totality is south of us, slicing northeast. Totality will be just south of Fort Smith. the closest centerline will be halfway between Russellville and Conway on I-40.
To get the best possible experience out of the pending eclipse, do a little planning. Think through what you want to do. Search the Internet for idea -- being sure to pick out reputable sites to study.
Enjoy the eclipse.
And, did I tell you to NEVER EVER NEVER NEVER EVER NEVER look at the without solar-safe glasses?
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Kent Marts is publisher and editor of The Weekly Vista. The opinions expressed are those of the author.
Editorial on 08/16/2017