On Monday, August 21, the sun will briefly be engulfed by the moon in a solar eclipse that will be visible from coast to coast in the United States.
“The eclipse is caused by the shadow of the moon hitting the Earth,” explained Prof. Gordon Stacey, astronomy. “The shadow of the moon is, of course, always there. The moon is going around the Earth, the Earth is going around the sun, and there’s always a shadow behind the moon. And if the moon happens to go directly between the Earth and the sun, that shadow will hit the Earth.”
Professor Phil Nicholson, astronomy, said that solar eclipses occur about twice a year somewhere on Earth, but because the eclipse path is typically very narrow, it is uncommon for them to occur in any particular spot.
“So they are quite rare by human standards, but they are common astronomically in the sense that if you count them happening anywhere on Earth, they are fairly regular phenomena,” he said.
This year, the eclipse path will start in Oregon and make its way across the country to South Carolina, according to the NASA website. Viewers along this “path of totality” will be able to see a total solar eclipse, in which the entire sun will momentarily disappear during the day, while other regions in the U.S., including upstate New York, will only be able to witness a partial eclipse.
“Unlike the total eclipse, which only lasts for a couple of minutes in totality, the partial eclipse lasts for almost three hours, so it’s quite a slow and gradual process and you don’t have to be observing at a particular moment to see it, but that also means it won’t be very apparent unless you’re actually looking at a picture of the sun,” Nicholson said.
About 70 percent of the sun will be blocked when the eclipse reaches its maximum in Ithaca. The eclipse is expected to begin at 1:17 p.m., will reach its maximum at 2:38 p.m. and will end at 3:54 p.m.
Ithaca residents may be out of luck, however, as according to The Weather Channel, there is a 45 percent chance of scattered thunderstorms in Ithaca around 2 p.m., and a 60 percent chance of scattered thunderstorms at 3 p.m.
Why Pay Attention?
The experience of viewing even a partial eclipse may provide a wonderful boost to one’s mental health, and Cornell Health clinicians highly recommend it, according to Sharon Dittman, director of community relations at Cornell Health.
“It’s rare that we have a moment when we are experiencing something at the same time,” she said. “That sense of participating in something bigger than yourself that doesn’t come along more than a couple times in a lifetime for most of us can really lift the spirit.”
In addition, Zachary Murray ’18, president of the Cornell Astronomical Society, said that taking a few moments to observe the eclipse could change the way that one might think about perspective in space.
“I think the cool thing about eclipses is that when you look at the sky it’s very 2-D, everything kind of looks like the same distance from you,” he said. “When you go to see an eclipse, it really forces you to think of space in a 3-D way because one thing is physically moving in front of the other. I think that’s a really cool perspective shift.”
What Will We See in Ithaca?
In Ithaca, people will be able to see the sky darken slightly during the day while the eclipse is occurring.
“I mean, it won’t get as dark as it would during an overcast day in Ithaca, for example,” Nicholson said. “So we can still walk around campus even on an overcast day without a flashlight because it gradually gets dark and your eyes dilate and just to the lower light levels. And the same thing happens during a partial eclipse. Because it happens slowly, your eyes adjust to it. I think you wouldn’t even notice it if you didn’t know it was happening, if you didn’t keep a watch on the sun in some form.”
Stacey added that the sun will appear crescent-shaped during this time, something that will be reflected by the spots of light coming through the trees.
“In Ithaca, what you’ll see that’s going to be strange is, even if you’re not aware of the eclipse, if it’s sunny, looking in the trees where there’s little spots of sunlight coming through the leaves, you’ll see spots on the ground that are not circular, but they have crescent shapes,” she said. “That is actually the image of the sun made by effectively a pinhole camera. So that’ll be kind of cool and kind of weird.”
Risks in Viewing the Eclipse
People who plan to observe the eclipse must make sure to take necessary precautions in order to protect their eyes from damaging sun rays.
“You can’t really feel injuries to your eyes, so something could be going wrong and you wouldn’t know it until late,” Murray said.
As tempting as it might be to witness the eclipse without proper protection, it could lead to temporary or permanent blindness.
“The lenses in our eyes act like a magnifying glass, one that is five times more powerful than a handheld magnifier,” Dittman explained. “Remember the experiment that shows a typical handheld magnifier focusing the sun’s light to burn holes in paper? That’s what happens when you look at the sun without eye protection.”
“You focus the sun’s light on the retina, burning holes in light-sensitive photoreceptor cells, causing solar retinopathy, a condition that can temporarily blind you, lead to missing spots in your vision, or even cause permanent blindness,” she added.
Dittman continued to explain that even though the sun will be blocked during the eclipse, it is sufficiently damaging to look at the sun whether 1 percent or 100 percent is visible.
“I think most of us learned as children from an adult in our life that you should never look directly at the sun,” Dittman said. “Instinctively, we close our eyes rather than look at the sun. When we hear that 70 percent of the sun is going to be blocked [with] the moon passing in front of it in Ithaca, New York, intellectually we may think that changes what we’ve known since we were little children about looking at the sun. However, the amount of light that comes from 30 percent of the sun is still more than enough to cause damage to our eyes.”
Dittman said that according to the Review of Optometry, “No definitive medical treatments [for solar retinopathy] currently exist.”
If someone were to accidentally or purposefully happen to look at the sun on Monday, Cornell Health recommends prompt consultation with an ophthalmologist, a physician who specializes in eye care and vision.
“Don’t risk it for a second, don’t risk for five seconds,” Dittman advised. “Know these other ways to experience the eclipse safely.”
Safe Ways to Experience the Eclipse
A few ways to view the eclipse safely include using special certified solar viewing glasses, making a pinhole camera, using welding glasses listed at #14 or higher, watching the eclipse on TV or online, or looking at a projection of sunlight through the leaves of trees.
In addition, representatives from the Cornell Department of Astronomy and the Cornell Astronomical Society will be gathering outside Fuertes Observatory to help people enjoy the eclipse safely.
“We’re expecting people will come out to the observatory on North Campus just because they tend to do that during celestial events, and we will have some small telescopes set up to project images of the sun so people can come and see them,” Nicholson said.
Karen Perez ’19, outreach coordinator for the Cornell Astronomical Society, said that Fuertes Observatory itself will not be open because hundreds of people are expected to show up and everyone will not be able to fit in the observatory. However, there will be volunteers outside the observatory passing out the special solar eclipse glasses.
“We will have volunteers, several professors from the astronomy department and Astronomy Society members, on the grounds of the observatory passing out eclipse glasses and we will have telescopes and binoculars with solar filters,” she said. “So our main purpose will be to distribute those solar eclipse glasses and explain to the public how to view the sun safely and answer any questions they might have.”
There will also be a viewing event in Stewart Park.
Total Solar Eclipse
As compared to a partial solar eclipse, Nicholson said that a total solar eclipse will be obvious to anyone in its path because the whole sun finally winks out in a matter of seconds and is completely gone for a couple of minutes.
“You basically go through a whole night-time cycle of twilight and nighttime, and the birds go to sleep and animals change, things like that, and the sun reappears a couple of minutes later and it’s like dawn,” Nicholson said. “It’s like going through a whole nighttime cycle in five or ten minutes or so with all sorts of interesting changes in the atmosphere and the sky. So apparently the whole physical experience of it is awe-inspiring.”
Stacey described the experience of viewing a solar eclipse during at the moment of totality as “primal,” and recounted a story of the time he witnessed a total solar eclipse in Manitoba, Canada in 1979 during his final year of college.
“I mean it’s scary because the sun is gone,” he said. “You see the sun blocked and you see this halo, which is gorgeous, suddenly come to light, and that’s the corona, and you feel kind of nervous. And that’s the point where you can actually look at the sun, because the whole photosphere, which is the very intense part, is blocked, and so then it’s safe.”
“But there is no time in Ithaca this year where it is safe, just to emphasize once again,” he added.
In order to see a total solar eclipse again, Stacey will be going to Omaha, Nebraska on Monday.
“Once you’ve seen one, you realize how different it is from a partial eclipse and you want to see more,” he said.
For those who will not be able to witness the total solar eclipse this time around, Stacey said that there would be another solar eclipse in seven years, on April 8, 2024, in which the path of totality will include upstate New York.
“It’s funny, I told my wife it was a once in a lifetime experience, and then we’re going all the way to Omaha to see this, we’re also seeing relatives there, and then it’s like ‘Wait there’s another one in seven years,’” he said.