Look! Up in the Sky! It’s a Solar Eclipse!

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A visualization of the earth, moon and sun aligned during a solar eclipse. Credit: NASA Scientific Visualization Studio

By Mahreen Khan

The celestial event of the decade, if not the century, will unfold on Monday when the Great American Eclipse will be visible across the United States. Although “the path of totality,” or the area in which a total solar eclipse will be visible, will stretch along a roughly 70-mile swath across 14 states, from Oregon to South Carolina, about 68 percent of the sun will be obscured by the moon on the South Fork.

It is expected that most eyes will be trained heavenward — covered with protective eyewear, hopefully — starting at 1:24 p.m., when the moon will begin to pass in front of the sun, through the peak at 2:46 p.m. and end at 4:01 p.m.

Dr. Daniel M. Davis, the chairman of the Stony Brook University Department of Geosciences, will be hiking along a portion of the path of totality in Idaho on Monday — making this his sixth total eclipse. He said total eclipses are rarer than partial eclipses, occuring about once every 18 months somewhere on Earth. Partial eclipses are visible — somewhere — about once every six months, he said.

RELATED: Where To Watch the Eclipse in and Around Sag Harbor

“I like to tell people that a total solar eclipse is the most exciting thing in nature that can’t kill you,” said Dr. Davis. “If you’re in totality, literally stars come out, you see the solar corona, you see very odd phenomena known as shadow bands on the ground.” Individuals along the path will see birds begin to roost and feel the temperature drop. On farms, cows will head back to the barn, while other nocturnal animals will begin to stir. The sounds of insects will change from their usual pitches. “Everyone located in the contiguous United States, plus parts of South America, Africa and Europe will be able to see at least a partial eclipse,” Dr. Davis said.

In Sag Harbor, there have been 35 partial eclipses visible over the past 100 years. Of those, at least 50 percent of the sun was obscured 17 times. If you miss Monday’s eclipse, your next chance of seeing a partial one on Long Island will be on June 10, 2121, when about 71 percent of the sun will be blocked. If you want to hold out for the next total eclipse that will be visible here, you will have to wait until May 1, 2079, according to the National Aeronautics and Space Administration’s JavaScript Solar Eclipse Explorer, a comprehensive web tool developed by NASA’s Chris O’Byrne and Fred Espenak.

David Kriegsman, at right, with mom Beth and brothers Benjamin and Roger at their North Haven home on Monday. Michael Heller photo

For those who don’t think they’ll make it 62 years, fret not. You can head down to Texas or out to the Rust Belt states or to upstate New York and New England when the next total eclipse will occur on April 8, 2024.

RELATED: Local Eclipse Chasers Follow the Path of the Sun

With all the hullabaloo around complex celestial interactions, it is important to understand what’s actually going on up in the sky. As Copernicus taught us, the Earth revolves around the sun once a year, spinning on its axis once a day. The tilt of the Earth’s axis is what determines which part of the Earth receives the sun’s direct rays, and in turn, which season Mother Nature bestows upon us. German astronomer and philosopher Johannes Kepler then discovered that planets revolve in ellipses that orbit sun. The sun rotates too, but at a much slower pace than the Earth. Add to that the moon, which rotates around the Earth, and you have the key players in place.

A solar eclipse is essentially the Earth passing through the shadow of the moon. For a solar eclipse to occur, three elements must be in place. First, it must be a new moon. Second, it must be a new moon in which the moon’s path intersects with that of the sun. Third, because the moon’s orbit is an elliptical one, everything must be lined up in such a way that the moon is near one of its two points of intersection, or nodes, when it is in the same plane as the Earth’s orbit.

This image of the moon crossing in front of the sun was captured on January 30, 2014, by NASA’s Solar Dynamics Observatory from its vantage point in space. Credit: NASA

During Monday’s partial eclipse, Sag Harbor will lie inside the moon’s penumbra, or outer partial shadow, which is why we will see only a certain percentage of the sun being photobombed by the moon. Since we are not in the path of totality, our view will be different and the effects we feel, subdued.

“Here on Long Island, it just won’t be that dramatic,” Dr. Davis said. This is especially true because only about 70 percent of the sun will be eclipsed. It’s when the sun is closer to being 90 percent eclipsed that real noticeable changes like a drastic dimming in light and a 360-degree view of the far horizon can be seen. “The sun will start to look crisp, though” Dr. Davis said, “and the day may just seem a little dim.”

RELATED: How to Properly View an Eclipse

Strange lighting effects, like shadow bands, may also occur, said Dr. Sten Odenwald, director of the NASA/Heliophysics Education Consortium’s citizen science directorate. Shadow bands are crescent-shaped sun images that reflect onto the ground, through gaps of leaves. “Humans are observers and their observations are flavored always by their emotional state,” Dr. Odenwald said. With just under three quarters of the sun’s diameter covered, some who are oblivious to the fact that an eclipse is ongoing may head outdoors Monday and think clouds are simply blocking the sun, said Dr. Davis. “But there’s all sorts of things here to be observed, if you choose not to be oblivious about it.”

People travel long and far for eclipses like this one, and have been doing so for centuries. For as long as we’ve had eclipse chasers, we’ve had people studying eclipses — dating back to the ancient Mesopotamians and Babylonians. By the 19th century, scientists had the ability to pinpoint where an eclipse would be, within a one or two-mile radius.

“You know, an eclipse doesn’t happen all the time and in any particular location there’s decades between eclipses,” said NASA data visualizer Ernest T. Wright, “and if it happens to be in your backyard you should go out and see it.” When, in Mesopotamia, centuries of eclipse records began to be compared, mathematical patterns and eclipses’ repetitious cycles became clear.

RELATED: Myth or Scientific Fact — How Well Do You Know Your Eclipses?

“There’s a period called the saros, which is 18 years, 11 days and 8 hours, where a solar eclipse will repeat at some point on the Earth,” Mr. Wright said. “People were predicting them 2,500-to-3,000 years ago, but we couldn’t do it really accurately until Kepler, who finally figured out that everything in the solar system orbits in an ellipse. And so that made all our predictions of where planets are and where the moon is, really accurate.”

The biggest takeaway, some scientists say, is that an eclipse viewing has the capacity to humble people, especially when it is a total eclipse. “A lot of people are profoundly affected by it, and I think that’s just because you suddenly realize you’re a tiny being on a planet in a very big space, and all these things are whirling around all the time but you’re not aware of them,” Mr. Wright said. Realizing how bright an object the sun really is, understanding the regularity with which these celestial events occur and reflecting on the wonderment of how accurate predictions can be, thanks to modern science, is what Dr. Davis, Dr. Odenwald and Mr. Wright say this eclipse is all about.

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