As just about all of America knows by now, a total solar eclipse will be visible across much of the U.S. on Monday, August 21.
Ahead of this big summer event, here are must-know facts about the solar eclipse -- and eclipses in general -- including how to protect your eyes (remember to never look directly at the sun without proper eye protection! The only exception is for the brief period of time when the moon has moved completely between the sun and the Earth.)
Read on to learn more.
1.) A solar eclipse occurs, on average, a couple of times a year. The moon passes between the Earth and the sun every 29 days, a time we know as "the new moon" -- when the moon is not visible in the sky at night. Yet the moon's orbit and the sun's path in our sky do not match up precisely -- so at most of those new moon events, the moon appears above or below the sun. "Twice a year, though, there is a period when the moon and the sun line up with Earth.
Astronomers call this an eclipse season," as Shannon Schmoll, director of the Abrams Planetarium at Michigan State University, told The Conversation. "It lasts about 34 days, long enough for the moon to complete a full orbit (and then some) of the Earth. During each eclipse season, there are at least two eclipses visible from some parts of the Earth. At the full moon, there will be a lunar eclipse, when the moon passes directly behind the Earth, resulting in a darker, reddish-colored moon. And at the new moon, there will be a solar eclipse, when the sun is blocked by the moon."
2.) We know in advance when eclipses will occur. Astronomers have precisely measured the motions of the Earth, the sun and the moon for centuries -- "including their orbital shapes" and other parameters, Schmoll told The Conversation. With that knowledge, "we can make mathematical models of their movements in relation to each other. Using those equations, we can calculate tables of data that can predict what we will see on Earth, depending on location, during an eclipse, as well as when they will happen and how long they last."
3.) After this eclipse, the next major solar eclipse in the U.S. will occur during two subsequent years. These will take place in 2023 and 2024.
4.) All of the hotels in Jackson Hole, Wyoming (as in many other cities) were sold out well ahead of time. There is an entire "eclipse schedule" at Teton Village, Wyoming (among many other places) for visitors -- it includes eclipse lift tickets, concerts with special guests, and unique sightseeing and viewing opportunities.
5.) This will be the first total solar eclipse within the continental U.S. in 38 years. The last one occurred on February 26, 1979. Before that, a total solar eclipse occurred on March 7, 1970. In addition, this solar eclipse's path of totality makes landfall exclusively within the U.S. -- the first such eclipse to do so since our independence in 1776.
6.) The last time a total solar eclipse was visible across the entire contiguous U.S. was during the June 8, 1918 eclipse.
7.) The path of totality will touch 14 states, though a partial eclipse will be visible in many other states. The event will begin on the Oregon coast as a partial eclipse at 9:06 a.m. PDT on August 21, and will end later that day as a partial eclipse along the South Carolina coast at about 4:06 p.m. EDT.
8.) Here are the 14 states in which the total solar eclipse can be viewed: Oregon, Idaho, Wyoming, Nebraska, Missouri, Illinois, Kansas, Kentucky, Tennessee, North Carolina, Georgia, South Carolina. Virtually all of these states have numerous public events planned for August 21.
9.) If you're going to view the total solar eclipse, you must protect your eyes. "Ophthalmologists and astronomers alike have been warning people to view the celestial spectacle only through proper solar filters that protect against the sun's rays," noted Time magazine. "Authentic glasses have lenses that meet the ISO 12312-2 standard" -- that's the international standard for safely viewing the sun.
"They'll usually look like cardboard 3D glasses," Time explained, "with much darker lenses than ordinary sunglasses, because they block 99.99 percent of the sun's rays. The eclipse glasses will also have labels that say they meet the ISO requirement, according to the American Astronomical Society (AAS). Customers will see ISO 12312-2 scrawled somewhere on the sides."
10.) The U.S. Postal Service has already released a special commemorative eclipse stamp. In June, the postal service released its Total Eclipse of the Sun Forever stamp to commemorate this August 2017 eclipse. When it's pressed with a finger, body heat will turn the black circle in the center of the stamp into an image of the full moon. The stamp image is a photo of a total solar eclipse seen in Jalu, Libya, on March 29, 2006, taken by retired NASA astrophysicist Fred Espenak.
11.) The eclipse will cause a reduction of solar power where the shadow reaches solar panels.
12.) One man has been to 27 total eclipses in his lifetime. Fred Espenak, the same retired NASA astrophysicist mentioned in point number 10 of this article -- and someone who has predicted the next 1,000 years of eclipses -- says he has "been to 27 total eclipses, and I've seen about 20 of them. Seven clouded out," as Vox reported. He also told the publication, "[During an eclipse,] you get an overwhelming sense of humbleness and how small and petty we really are compared to the mechanics of the solar system, the clockwork of the universe. These events that are taking place ... in no way can we affect or stop [them]. It gives us a sense of how tiny we are and yet how we're connected to the whole system. All this happens all at once."
13.) Animals may behave oddly during the eclipse. "It really is an awesome experience to stand in the shadow of the moon and see ... remarkable phenomena" -- including weird behavior from animals, Rick Fienberg, press officer for the American Astronomical Society, told mic.com. While there hasn't "been a lot of serious research done on animal behavior" during a solar eclipse, said Fienberg, "a handful of observational reports have cropped up over the last few decades. There are stories of sudden silence from screeching cicadas in Tuscon, Arizona, starting when the sun was about 50 percent covered by the moon, for example. And as a false sense of night drew near, bees in India grew restless and started leaving their hives, and captive squirrels in California reportedly became more active."
14.) The solar eclipse of 1919 was seen as a triumph of science -- "while the ancients viewed eclipses as signs of great acts of God," according to space.com. During the 1919 eclipse, "in which the sun vanished for six minutes and 51 seconds, scientists measured the bending of light from the stars as they passed near the sun. The findings confirmed Einstein's theory of general electricity, which describes gravity as a warping of space-time," noted the publication.
15.) During the moment of total solar eclipse on August 21, stars will be visible. So will the planets Venus, Mercury, Mars and Jupiter.
sources: The Conversation, jacksonhole.com, cs.astronomy.com, Time.com, USPS, vox.com, mic.com, space.com, wyff4.com
(photo credit, homepage images: Danielparker, Flickr; photo credit, article image: Tomruen, Wikimedia)