Safely Watching the August 21st Solar Eclipse

August 10, 2017

On August 21, 2017 you will have a once-in-a lifetime opportunity to view a powerful solar eclipse. A solar eclipse occurs when the moon gets directly in between the Earth and the sun, blocking the sun’s rays. The darkness that results is a rare occurrence, especially in the Chicagoland area. While solar eclipses happen a few times every year, the path of totality, or total darkness, spreads over less than 1% of the Earth’s surface and only occurs for a few minutes. For example, India or Cambodia might experience a wonderful eclipse that we would never experience in the U.S. In addition, eclipses often take their path of darkness over the world’s oceans since our planet is mostly water.

Fun Facts

• In Chicago, 87% of all sunlight will be blocked at 1:19 pm on August 21.
• The last time this much sun was blocked in Illinois was in August of 1869!
• It has been 99 years since the last total eclipse to go coast-to-coast across the United States.
• There will be two more total solar eclipses to touch Illinois in the next 50 years, on April 8, 2024 and October 17, 2153
• The odds of witnessing a total solar eclipse precisely where they live are approximately three times every 1,000 years.
• The moon’s 73-mile-wide shadow will travel at up to 1,200 m.p.h.
• As night occurs at 1:21 pm in the afternoon in southern Illinois, street lights will come on and roosters will get confused a few minutes later!

 

Viewing Tips
The sun’s powerful rays can be very damaging to the eye’s retina. For this reason, one should never look directly at the sun. Fortunately, there are several ways to safely experience the upcoming solar eclipse

1. Solar Eclipse Viewing Glasses
The American Astronomical Society (https://eclipse.aas.org/resources/solar-filters) is a great resource for reputable retailers who sell solar glasses and viewers. These products have been verified by an accredited testing laboratory to meet the ISO 12312-2 international safety.
This is the only safe way to look directly at the sun. Sunglasses or welder’s shields will not protect your eyes from the powerful UV light that comes from the sun. Homemade telescope and camera filters arealso dangerous.This does not constitute medical advice. Readers with questions should contact a qualified eye-care professional.

In the Chicagoland area, you must always use a safe solar filter to view the sun directly. For eyeglass wearers, put your eclipse glasses on over them, or hold your handheld viewer in front of them. If you are fortunate enough to travel to the areas of totality where 100% of the sunlight gets blocked (See map), you can safely remove your solar glasses at full totality when the moon completely covers the sun. As soon as the bright sun begins to reappear, replace your solar viewer to look at the remaining partial phases. (https://www.timeanddate.com/eclipse/make-pinhole-projector.html)

2. Pinhole Projector
Materials

• pieces of stiff white cardboard, e.g. 2 paper plates
• alternatively, 2 sheets of plain white paper
• a thumbtack, a sharp pin, or a needle

1. To make a quick version of the pinhole projector, take a sheet of paper and make a tiny hole in the middle of it using a pin or a thumbtack. Make sure that the hole is round and smooth.
2. With your back towards the Sun, hold 1 piece of paper above your shoulder allowing the Sun to shine on the paper.
3. The 2nd sheet of paper will act as a screen. Hold it at a distance, and you will see an inverted image of the Sun projected on the paper screen through the pinhole.
4. To make the image of the Sun larger, hold the screen paper further away from the paper with the pinhole.

 

3. Box Projector
A sturdier version of the pinhole projector is the box projector. (https://www.timeanddate.com/eclipse/box-pinhole-projector.html)

Materials

• a long cardboard box or tube
• scissors
• duct tape
• aluminum foil
• a pin or a thumbtack
• a sharp knife or paper cutter
• a sheet of white paper

1. Cut a rectangular hole at the end of the box. You can tape 2 boxes together to make a long box. The longer the box, the larger the projected image.
2. Use the scissors to cut out a piece of the aluminum foil slightly larger than the rectangular hole. Make sure the foil is completely flat and not crinkled.
3. Tape the foil over the rectangular hole in the box.
4. Use the pin to poke a tiny hole in the center of the foil.
5. Tape the sheet of paper on the inside of the other end of the box.
6. Stand with your back toward the Sun. Place the box over your head with the pinhole towards the Sun. Adjust your position until you see a small projection, a negative image, of the eclipsed Sun on the paper inside the box.

 

4. Adler Planetarium Solar Party
The Adler is hosting Chicago’s biggest eclipse block party featuring all things solar with FREE outdoor activities and safe viewing of the Sun and the eclipse! Join fellow Chicagoans and visitors to share this spectacular celestial experience together as a community. They are setting up under the Sun and filling their parking lot with programming from partners from across the city. Enjoy live entertainment, hands-on science for all ages, local food trucks, eclipse updates, and more. Additionally, all guests will get #EquippedToEclipse with free safe solar viewing glasses while supplies last.

A solar eclipse is one of Mother Nature’s grandest events. Please follow these simple rules and you can safely enjoy the spectacle and have memories to last a lifetime.