Pre­pare Now For The Eclipse

McDonald County Press - - COUNTY - Kent Marts

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 so­larsafe 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 lives.

If you do not have so­larsafe 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.

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 an 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 McDon­ald County High School park­ing lot, the eclipse starts at 11:42.27 a.m., reaches max­i­mum at 1:11.31 p.m., and ends at 2:39.44 p.m.

At 1:11 a.m., 93.4 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, Wy., 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 of 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 McDon­ald County High School will see nearly 97 per­cent of the sun cov­ered by the moon.

In 2024, the path of to­tal­ity is south of McDon­ald County, slic­ing north­east. To­tal­ity will be just south of Fort Smith, Ark., the closest cen­ter­line will be half­way be­tween Rus­sel­lville, Ark., and Con­way, Ark., 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 ideas — 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 sun with­out so­lar-safe glasses?

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