A Total Eclipse of the Sun
● By Sandy Kauten
Now’s the time to plan for your eclipse moment. Where will you be for this once-in-a-lifetime event? What, exactly, will you be seeing? And what’s the best way to view it?
What is an eclipse?
From our perspective on earth, we can see lunar (moon) eclipses and solar (sun) eclipses. These happen when the sun, the moon, and the earth are in line with one another and the light from the sun casts a shadow from one body onto the other.
A lunar eclipse happens when the sun casts the shadow of the earth onto the moon. It may cover part (which is a partial lunar eclipse) or all of the moon (a total lunar eclipse). These kinds of eclipses seem pretty common, because lots of people can witness them at the same time: The earth’s shadow is so large against the moon that an entire hemisphere, weather permitting, can witness the eclipse all at once.
A solar eclipse occurs when the moon passes between the earth and the sun. The sun casts the moon’s shadow onto the earth. From earth, the moon appears to cover the sun. Because the moon is so small in comparison, the shadow the sun creates is small and it travels in a very narrow path on the earth. This path of totality is where you want to be in order to witness a total solar eclipse.
Sometimes the moon is not entirely in line and we will see it cover only a part of the sun. This is a partial solar eclipse. An annular solar eclipse occurs when the moon is farther away and is too small to “cover” the sun—we can still see a ring of bright sunlight around the shadow of the moon when this happens.
How should I prepare?
To fully and safely view a total solar eclipse, there are two key steps: be in the path of totality and protect your eyes.
It is not enough to be near the path of totality—you need to be right in it! In Oregon this August, the path of totality will touch several major sites: Lincoln City, Newport, Salem, Corvallis, Albany, Madras, John Day, and Prairie City, to name a few. Eugene, Springfield, and Portland are not in the path, so folks from those cities will need to take short trips to view the event.
Eye safety is paramount when viewing an eclipse. Looking directly at the sun—even just a small part of it for a short time—can permanently damage your eyes. The only safe ways to view an eclipse are through special solar filters (which can be used on cameras or eyeglasses, for example) or by pinhole projection.
Eclipse-viewing glasses can be purchased online. Regular sunglasses—even dark ones or multiple pairs—are not safe for eclipse viewing. Do not look at the sun through binoculars, camera lenses, or any other magnifying viewer without proper filters.
Pinhole projection is a tried and true method of safe eclipse viewing. With this method, you view the sun projected through a small hole onto a flat surface—like a movie on a screen. Want to make your own eye-friendly eclipse viewer? Join us at the museum next month for our June 3 family day. We’ll have a station set up especially for making viewers, and you can take yours home with you for the big day!
During a total eclipse, like this one, it is safe to look up only when the sun is entirely covered by the moon and darkness falls. This will last for a minute or two, depending on your vantage point. When the sun begins to peek back around the moon, it’s time to use your glasses or projector again.
Where can I learn more?
NASA has a website devoted to this eclipse. Check it out at eclipse2017.nasa.gov. You can find maps of the path of totality, animations of eclipses, and much more.
For some hands-on learning and other eclipse-related fun, head to the Museum of Natural and Cultural History for Exploring the Extraordinary—A Total Solar Eclipse Family Day on Saturday, June 3 from 11:00 a.m. to 3:00 p.m. Enjoy an astronomically fun day of crafts and activities exploring stars, planets, and celestial events, and tour the new National Geographic exhibit Rarely Seen: Photographs of the Extraordinary.
The Museum of Natural and Cultural History is located at 1680 E. 15th Avenue, on
the UO campus. Museum hours are Tuesday through Sunday from 11:00 a.m. to 5:00
p.m. Visit us online at natural-history.uoregon.edu.
by Hannah Kruse