Hows, whys and wheres of the solar eclipse

On Monday, Aug. 21, at about 1:25 p.m., the sun will slowly disappear from the skies over the Tri-state region. Few, if any, residents will think it’s being eaten by dragons and start banging drums to scare them away. The idea of a solar eclipse is well-known. Less well-known is precisely what causes a solar eclipse and what to expect when one occurs. The Lakeville Journal Co., spoke with Kristen Larsen, professor of astronomy at Central Connecticut State University, to find out.

What causes an eclipse

Larsen began with the basics.

“As you know, the moon goes around Earth, and Earth goes around the sun.” 

The two orbits are not in the same plane; think of one Hula Hoop inside another but at  different angles. 

“So only under very special circumstances do all three objects line up. When that happens, you can have an eclipse.

“If you have the sun, then Earth, then the moon, in that order, Earth casts a shadow on the moon. People on Earth see the moon blocked out. That’s a lunar eclipse.

 “If you have the sun, then the moon, then Earth, the moon casts a shadow on a very small part of Earth. The people in that little tiny shadow will see the sun blocked out. That is a solar eclipse.”

Many of us have seen one or more lunar eclipses, but the solar eclipse experience is much more rare. There’s a reason for that.

“In order to view a lunar eclipse, you have to be in Earth’s shadow. And ‘in Earth’s shadow’ means basically the nighttime side of Earth. That’s half the planet. But if you want to see a solar eclipse, you have to be in the shadow of the moon. And because that shadow is much smaller than the surface of Earth, it’s less likely that you’re going to be in the area that can view a solar eclipse.”

Who will see what

“We are going to be in the moon’s shadow, but not the middle part of the shadow. The shadow has two parts: the umbra and the penumbra.”

Umbra means “dark” in Latin, and penumbra means “almost dark.” As Earth rotates, the shadow seem to move across its surface.

“The umbra, the part where everything is perfectly lined up, is about 70 miles wide. For this particular eclipse, the path stretches diagonally across the United States from Oregon down to South Carolina. Only people in that narrow swath are going to see the sun completely eclipsed. 

“Above and below that swath, people are going to see part of the sun eclipsed. The farther away you are, the less of the sun you will see eclipsed. In Connecticut, we are going to see about two-thirds of the sun eclipsed.”

Believe it or not, if you’re sitting in your home or office when this happens, you might not notice much.

“It might get a little dimmer out, and the light gets a kind of a metallic blue tint to it. Imagine those movies like ‘300,’ where they color things weirdly. It’s not that dramatic, but the light gets a strange quality to it.”

Still, it’s not going to be as dark as, say, twilight. But there may be other effects as well.

“You might notice the weather change a little bit. The wind, and maybe the temperature, might change a little bit.”

How to watch it, safely

To tell that there’s an eclipse going on, one has to see the disappearing sun. And there are only two ways to do that without damaging your eyes.

The first is to have solar eclipse glasses, which are like 3-D movie glasses but dark. They block out all but a tiny portion of the light that strikes them, enabling you to safely look directly at the sun.

Larsen is adamant that people using eclipse glasses should not mess around with telescopes, binoculars or cameras.

“When you look through those solar viewing glasses, you are not going to be able to see anything through them except the sun. You won’t be able to see your camera. The problem is that people will be tempted to briefly lift their viewing glasses, or jury-rig their glasses on the camera, and they’re going to accidentally look at the sun.”

Is a brief glimpse really that bad? Yes.

“In just about every eclipse, people go blind because they do something stupid.”

If you’re going to get eclipse glasses, don’t buy them from a convenience store.

“NASA has issued a warning that supposed solar viewing glasses of unknown quality have been hitting the market. You have to get them from a reputable source. And if there are any cracks, holes, crinkles, anything in the filter material, throw them away.”

Two pinhole projectors

The other safe way to watch the sun disappear is to buy — or, more likely, build — a pinhole projector. Any number of different designs are available on line.

“The very simplest thing is to take two pieces of cardboard. Poke a pinhole in the first one. Then turn your back to the sun and hold that piece of cardboard so that the sun shines through the pinhole. Then take the second piece of cardboard and use it as a screen. The image of the sun projected on that screen is perfectly safe to look at. 

“The size of the image depends on how far apart you can hold your hands. If the two pieces of cardboard are a yard apart, the size of the sun’s image will be about three-quarters of an inch. So it’s not huge, but it’s definitely big enough to see what’s going on.”

If you don’t want to hold your hands far apart for the duration of the eclipse, you could build a projector from a cardboard mailing tube — the longer the better.

“They usually have two white end caps. Take off one of the end caps, cover the open end with a piece of tin foil, and poke a pinhole in the tin foil. Leave the second end cap on, because that’s going to be your screen. All you need to do is cut a little viewing slot about an inch from the end cap so that you can see the inside surface of the cap. It doesn’t have to be large, maybe one inch by two inches or whatever; you can play around with it.”

To watch the eclipse, put the tube on your shoulder with the tin-foil end pointing up and back. Stand with your back to the sun, then move the tube so as to minimize its shadow on the ground. When the shadow is just a circle, the image of the sun will be projected on that end-cap screen.

Totality: Worth it

Despite being a native of Connecticut, Larsen will not be watching this eclipse from her home state. 

“There is nothing that could keep me here,” she said.

Is the difference between a partial and a total eclipse enough to justify traveling 800 miles or more?

“There is no comparison in my book. Even 90 percent eclipsed is not the same as totality. There is nothing like a total solar eclipse. I turn into a ball of 5-year-olds when I’m in the middle of one.

“But people have to balance that with their own comfort and sanity. At this point, dropping everything and driving to totality might not be a practical thing to do.” 

Still, she said, “if you have a friend or relative in the path of totality and you can get there, certainly go and make a vacation of it. If you can get to the path of totality, it is definitely worth your while to do it.”

Larsen is quick to warn of the non-astronomical effects that might accompany a total eclipse.

“You don’t know how bad the traffic’s going to be. There may be price gouging. Things like this can bring out the best in people and they can bring out the worst in people.

“If you’re going to the path of totality, you should make sure you have food and water and whatever plans you would normally have if you were stranded anywhere for a day or two. Because you never know.”

Despite these cautions, Larsen doesn’t want to discourage anyone.

“You should bring your patience and, no matter what happens, enjoy the eclipse. Whether you get to see totality, or you get to see partial, or you get to see only part of it because the clouds come and go, just enjoy it. Enjoy the festival nature of it.”

Second chance

If you’re going to miss this eclipse for whatever reason, don’t fret.

“There is going to be another solar eclipse on April 8, 2024. That one is going to come a lot closer to our neck of the woods.” Over Connecticut, the sun will be more than 90 percent eclipsed. And if you don’t mind a little bit of traveling, “the band of totality is going to be as close as western New York state and the tops of Vermont, New Hampshire and Maine.”

For maps of this month’s eclipse’s path of totality, go to www.eclipse2017.nasa.gov/eclipse-maps. For links to reputable vendors of solar eclipse viewers, go to www.eclipse.aas.org/resources/solar-filters. For links to information about both eclipses, go to www.ccsu.edu/astronomy and scroll to the bottom.

To watch the eclipse online, NASA has a web page devoted to the eclipse with loads of information on it; go to www.eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle2001/SE2017Aug21Tgoogle.html.

The Connecticut Science Center (in partnership with a media company called Slooh) is also planning to broadcast the eclipse, from an Air Stream trailer parked in Stanley, Idaho, at Elk Creek Campground, where there will be a three-day eclipse festival. The trailer is leaving the science center on Aug. 7 and will broadcast from the road as the team on board makes its way to Idaho. 

There will also be a celebration on Aug. 21 at the Connecticut Science Center, which is in Hartford, with a DJ, educational activities, crafts and yoga with Vasu Tribe Studio. The Slooh live-stream feeds will also be shown at the center during the celebration. 

For more information on the Connecticut Science and the Total Eclipse Celebration, call 860-724-3623 or go to www.CTScienceCenter.org.