Here’s your guide to understanding, safely viewing solar eclipse in Columbus area

Aug. 21 will be the first time in 38 years a total solar eclipse will be observable anywhere in the U.S., and it’s the first time in 99 years the path of totality will cross the continent from one side to the other.

In Columbus, the eclipse will begin at 1:05 p.m., with the Moon starting to block some of the Sun, and last until 4:03 p.m., when the last part of the Moon move past the Sun. The maximum eclipse in Columbus will occur at 2:37 p.m., when the Moon will block 92 percent of the Sun, according to Shawn Cruzen, executive director of the Columbus State University Coca-Cola Space Science Center.

“From 2 to 3 is the prime window here in Columbus,” Cruzen said during his Aug. 3 lecture in the Columbus Public Library.

And hope for clear skies.

“Cloudy day,” Cruzen said, “we’re a bust.”

Here’s your guide, courtesy of Cruzen, to understanding the eclipse and how and where to view it safely.

Perspective

An estimated 78 million people are expected to “find their way into the path of totality,” Cruzen said, perhaps creating the world’s largest traffic jam.

The eclipse has “captured America’s imagination,” Cruzen said, because “it’s going to provide for those folks who can get in the path of totality an absolutely one-of-a-kind amazing view of a celestial object. … When you see something like this, it’s a very visceral experience. Yes, it’s a scientific experience, but it’s also kind of an emotional connection to nature.”

The closest location to Columbus where the total eclipse will be visible is in Helen, Ga., and Nashville is the largest city along the path, Cruzen said.

Cruzen has been an astronomer for more than 30 years, but he’s never seen a total solar eclipse in person. He plans to be “somewhere in the great state of Wyoming” to view the eclipse in the path of totality.

A total of 13 CSU researchers are scheduled to be stationed around the country then. The photos and videos collected will enable CSU to produce a webcast of the eclipse and lead to student research projects and a planetarium show, Cruzen said.

Safety

“It’s more dangerous to look at the Sun on a day when it’s not an eclipse, because then you have 100 percent of the Sun coming through,” Cruzen noted. “But the problem occurs here, when you get close enough to partial (eclipse), you actually begin to lose your blink instinct. As the Sun dims down, your retina has its own nerve endings, so you might be tempted to look up there, because you can and not feel pain, and the blink instinct doesn’t kick in with a dimmer Sun. Now that is when an eclipse can truly be more dangerous.”

He emphasized, “So even at that 92 percent (eclipse in Columbus), do not look at the Sun unprotected.”

Cruzen provided the following tips for safely viewing the solar eclipse:

▪ Solar glasses should have the ISO (International Standards Organization) reference number 12312-2 printed on the glasses. Never use these glasses in conjunction with an unfiltered optical device, such as binoculars or a telescope. The CCSSC gift shop is selling them for about $4 – “we just ordered 2,000 more of them,” Cruzen said. – but retailers around town are selling them cheaper, he added.

▪ Never look at the Sun through an optical device, such as binoculars or a telescope, without a front-end solar filter, even with a filter on the eyepiece or on your face.

▪ As for using a cellphone camera to view the eclipse, Cruzen said, “As long as you’re not looking with your eye, the issue isn’t safety. It’s whether or not you melt your camera. Prolonged exposure of your cellphone to the Sun will eventually cause it to be damaged. But quick shots of the Sun would probably be OK. And I do mean quick. But remember: Don’t look at the Sun (without proper protection) when you’re trying to point your camera.”

▪ Pinhole projection is the least expensive and safest way to experience the eclipse. The easiest way is to take two pieces of cardboard, poke a round hole in one of them and let the Sun shine through the hole onto the other piece. Thin cardboard works best to get an even hole. White cardboard works best to display the projected image.

Activities

The following eclipse activities are scheduled in Columbus:

▪ Aug. 17 at noon in the Columbus State University Schwob Library, Coca-Cola Space Science Center external programming director Michael Johnson will speak about what to expect during the eclipse. Free and open to the public, including lunch.

▪ Aug. 21, from 1-4 p.m., in the CSU Coca-Cola Space Science Center, view the eclipse in a variety of ways, such as CSU’s webcast, look through a solar telescope or purchase a pair of eclipse viewing glasses while supplies last. Officials will simulcast the webcast onto a large video screen inside University Hall Auditorium, which will be open to the public on CSU’s main campus. The Columbus Public Library also plans to show the webcast.

Details

The eclipse shadow moves across the surface of the Earth at something like 14,000 mph, Cruzen said.

“If you think about it,” he said, “you’re talking about two very tiny circles in the sky. Your pinky finger can cover it up.

Cruzen offered an analogy to explain the Sun and the Moon take up only half a degree across the sky.

“There’s 360 degrees in a circle,” he said. “So take a pizza, chop it into 360 slices and serve it to your friends. They won’t like that. Take one of those pieces and chop it in half, that’s half a degree. It’s a whisker-thin slice, so they don’t line up very often.”

Combining the speed and size, that’s why, over the wide course of the entire surface of the Earth, the eclipse is only a 70-mile-wide path and totality will last for only 7 minutes at most and for viewers in America a maximum of about 2½ minutes, Cruzen said.

The Moon must be in new phase for a solar eclipse to occur, Cruzen said. The new phase happens once a month, but a solar eclipse doesn’t occur every month because the plane of the Moon’s orbit is tipped by 5 degrees compared to the Earth’s orbit around the Sun. “You’re talking about tiny little spheres (as they appear in the sky) orbiting at really large distances, so 5 degrees ends up being a gigantic amount,” Cruzen said.

The orbits of the Earth and the Moon have two crossing points, called nodes, Cruzen said. One is considered an ascending node, the other a descending node.

“Those two things happening at the same time makes it a lot more rare: new phase and at one of the nodes,” Cruzen said.

In Columbus, he said, “Our part of the Earth will be located underneath the penumbra shadow, so we’re going to see a partial eclipse, albeit a really great one.”

The Moon must be in full phase for a lunar eclipse to occur, when the Earth blocks the Moon’s sunlight and casts a shadow on the Moon.

“The Earth can make a giant shadow for the Moon to move into,” Cruzen said. “So during lunar eclipses, half the world sees them simultaneously. The whole side of the Earth facing away from the Sun gets to see a lunar eclipse, as long as it’s not cloudy.”

Comparatively, the Moon’s shadow (umbra) is much narrower in a solar eclipse. It forms “a pencil-thin beam of shadow that passes across the surface of the Earth,” Cruzen said. “That’s why it only covers a little tiny portion. That’s why seeing a total solar eclipse is so much more rare.”

An annular solar eclipse is when the Moon is farther away from the Earth and appears smaller in the sky than during a total solar eclipse so it doesn’t completely block the Sun; it appears to form a ring of fire instead.

“There are two eclipse seasons for each eclipse year, and there are two or three eclipses per season,” Cruzen said. “So there are as many as six eclipses in a single year. Therefore we have at least four eclipses of some kind, partial or total, lunar or solar, visible somewhere on the Earth every year.”

Total solar eclipses happen somewhere on Earth about every 18 months, Cruzen said, so why do they seem so rare?

“If you don’t travel to see eclipses, you only get a lunar eclipse at your house about every three years,” Cruzen said. “… You only get a total solar eclipse at your house about every 375 years.”

The next total solar eclipse that will be observable in Columbus is expected on May 11, 2078, “so you’re almost there,” Cruzen said with a laugh.

“Our Sun is 400 times bigger than the Moon, but it’s almost exactly 400 times farther away,” Cruzen said. “I don’t want that coincidence to escape you. We live on a planet that has a moon that’s exactly 400 times closer yet 400 times smaller than our sun, which is why you can have them perfectly match up in the sky together. That doesn’t happen anywhere else in our solar system, for that matter anywhere else that we even know about.”

According to EarthSky.org, the Moon is moving farther from Earth by about 4 centimeters per year. That means all solar eclipses were total eclipses eons ago and all solar eclipses will be annular eclipses eons from now, the website says.

This story was originally published August 14, 2017 at 1:47 PM with the headline "Here’s your guide to understanding, safely viewing solar eclipse in Columbus area."