News

The Eclipse in Sun Country

Monday, Aug. 21

By Bob Naeye

Partial eclipse in Italy. Photo: Giorgio Galeotti.Partial eclipse in Italy. Photo: Giorgio Galeotti.On Aug. 21, 2017, a major astronomical event will take place in the United States for the first time since our nation was engaged in World War I. A total solar eclipse will race across the mainland from coast to coast.

People inside a roughly 70-mile-wide path running east-southeast from Oregon to South Carolina will witness the incredible spectacle of the moon fully blocking the sun. This cosmic coincidence results from the fact that the sun is 400 times larger than the moon and 400 times farther away — meaning the two bodies appear almost identical in size as seen from Earth.

The eclipse will only be partial in our region of Pennsylvania. But if the skies are clear that afternoon, you can still be mesmerized by following the moon as it creeps across the sun over the course of about 2 hours and 41 minutes. 

The eclipse gets underway the moment the moon starts taking a tiny “bite” out of the sun. The exact time this will happen will vary by several seconds depending on your exact location. The eclipse starts at 1:17:43 p.m. in downtown Hummelstown, 1:17:50 in Hershey, 1:17:52 in Palmyra, and 1:18:00 in Elizabethtown.

This image – taken by Mario Motta, an amateur astronomer from Gloucester, Mass. – shows the sun 75 percent eclipsed. The sun will be approximately 77 percent eclipsed in Sun Country.This image – taken by Mario Motta, an amateur astronomer from Gloucester, Mass. – shows the sun 75 percent eclipsed. The sun will be approximately 77 percent eclipsed in Sun Country.Over the course of an hour and 20 minutes, the moon will cover more and more of the sun, giving the sun a surreal crescent appearance. At its maximum, the moon will cover nearly 77 percent of the sun. This won’t be enough to produce a noticeable darkening of the daytime sky, but you might feel a slight cooling effect.

And then over the next hour and 20 minutes, the sun’s crescent shape will appear to open up minute-by-minute. The moon will leave the sun behind, ending the eclipse, at 3:59:09 p.m. in Hummelstown, 3:59:10 in Hershey, 3:59:11 in Palmyra, and 3:59:30 in Elizabethtown.

If you’re planning to view the eclipse somewhere else, you can easily find out the exact start, maximum, and end times by visiting NASA’s interactive website at https://eclipse2017.nasa.gov/sites/default/files/interactive_map/index.html. If you’ll be in the Eastern time zone, subtract 16 hours to convert Universal Time to your local afternoon time.

View the Sun Safely

As with any eclipse, it’s critically important to take proper precautions to observe the sun safely. The sun’s intense light can quickly cause permanent damage to a person’s eyesight, even when it’s mostly blocked by the moon. Never look at the sun directly for more than a second unless you use proper filters.

The easiest and most direct way to view the sun safely is to acquire a pair of eclipse glasses. These glasses block all but a tiny fraction of the sun’s light, making it perfectly safe to look at the sun directly for hours. But only use eclipse glasses with your naked eyes; do not use them with a telescope or binoculars. And make sure there are no holes in the film.

You can order these inexpensive glasses at websites such as Amazon.com or GreatAmericanEclipse.com. Alternatively, you can pick up a free pair at the Hershey Public Library or the Palmyra Public Library. But a note of caution: supplies at both libraries are limited, and the Palmyra library will be distributing glasses only on eclipse day.

A safe indirect method for viewing the eclipse is to create a miniature pinhole camera. Punch a tiny hole in a sheet of paper and let the sun’s light pass through the hole and shine onto a white sheet of paper. You’ll be able to follow the entire progression of the eclipse with this method. If you’re near a tree, its leaves will act as natural pinhole cameras, casting countless crescent suns on the ground.

Observing the eclipse with a telescope or binoculars will magnify the image of the sun, providing a significantly more detailed and dramatic view. But you’ll also be intensifying the sun’s harmful rays. If you plan to use optical aid, it’s vitally important to put a safe solar filter on the front end of a telescope, or in front of both lenses in a pair of binoculars.

Telescope supply stores and websites offer a variety of safe solar filters. Some exotic filters will provide amazing views of the sun, but can get costly. The least expensive option is to buy Baader AstroSolar Safety Film (or a comparable product), which looks and feels like aluminum foil. You can tape this film over the front of the telescope, or over both lenses of binoculars. Make sure there are no holes in the film.

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If you’re interested in photography, spend the time between now and Aug. 21 to practice photographing the sun in the early and mid-afternoon. Try different filters, exposure lengths, focal lengths, and ISO settings to determine ahead of time which will combinations produce the best pictures of the sun. Websites such as MrEclipse.com and Eclipse-Chasers.com offer excellent advice from experienced eclipse photographers.

The Aug. 21 eclipse will be the first to touch the U.S. mainland since 1979. The path of totality crosses 14 states (although just tiny portions of Montana and Iowa) and five state capitals. Nashville, Tenn., is the largest city to lie entirely within the path of totality. About 12 million people live inside the path, and millions more will travel from all over the world to catch this rare spectacle. This will be the first solar eclipse in which totality can be seen exclusively from the U.S. since we became a sovereign nation in 1776. 

University of Redlands astronomer Tyler Nordgren predicts this "Dream American Eclipse” will be the most photographed, shared, and tweeted event in human history.

A typical location on Earth gets one total solar eclipse every 375 years on average. The last total eclipse to pass over the Hershey-Hummelstown-Palmyra area occurred in 1478 — before Columbus’s first voyage to America. The next won’t occur until 2144 — when nobody reading this article will still be alive.

If you miss the Aug. 21 eclipse, you’ll have a chance to see another total solar eclipse on April 8, 2024. The path of totality will cross the U.S. from Texas to Maine, and will include a small portion of the very northwestern corner of Pennsylvania, in and around Erie. Our area will be treated to a very deep partial eclipse, with about 92 percent of the sun being blocked by the moon at maximum.
 
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Viewing the Total Eclipse

I have traveled to distant locations five times to observe total solar eclipses. Partial solar eclipses are interesting, and well worth your time and effort to observe. But like anybody who has seen a total eclipse, I cannot stress enough that there’s an enormous difference between a partial eclipse and a total eclipse. 

The difference between a total solar eclipse and a 99 percent partial solar eclipse is like the difference between a spectacular July 4 fireworks display and a firefly. Or it’s like the difference between watching the Super Bowl live versus watching a preseason NFL game on a small black-and-white TV.

It’s absolutely worth your time and effort to do whatever you can to get inside the path of totality at the time of the eclipse. People inside this narrow path will be dazzled by the unforgettable spectacle of a pitch-black hole in the sky surrounded by the diaphanous whitish glow of the solar atmosphere (the corona). There’s no other sight like this in the world, or in the entire solar system.

If you travel into the path of totality, it’s perfectly safe to remove your eclipse glasses or filters and view the eclipse with your naked eyes or with binoculars once the sun is completely blocked at totality. In fact, if you use a filter during totality, you’ll see nothing at all. If you’re near the center of the narrow path, totality will last about 2.5 minutes depending on your exact location.

The eclipse will be a spectacular event only if the sky is clear. In general, the Western U.S. has the best weather prospects. But no matter where you go, check the weather forecast the night before the eclipse, and drive to an alternate location with better prospects for clear skies at eclipse time. With millions of eclipse chasers from all over the world expected to be in the path of totality, be prepared for heavy traffic.

No photograph has ever captured the full drama and beauty of a totally eclipsed sun as seen with the naked eye. But if you want to take pictures, my advice is to spend almost all of your time actually looking at the eclipse and not wasting this precious time by fiddling with camera equipment.


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