The total solar eclipse that will cross much of the continental US on Monday, along with parts of Mexico and Canada, will be one of the most spectacular celestial events in recent memory. Here’s what you need to know:
What is a total solar eclipse?
The phenomenon occurs when the moon moves in front of the sun, completely blocking its face, causing the clear sky to darken to dusk in just seconds. The trail of the moon’s shadow is called the path of totalitywhich for Monday’s eclipse will be about 115 miles wide and sweep across 15 states in the US in a northeasterly direction, from Texas to Maine, for about an hour, starting at 1:30 pm CT and ending at about 3:00 pm CT: 35 ET.
How rare is it?
The most recent total solar eclipse in the US was in 2017, but an interval of only seven years is unusual. The previous one before that occurred in 1979, and the next one visible in the contiguous US won’t be until August 2044. Only 16 other total solar eclipses have occurred over at least part of the lower 48 states in the last 155 years.
Didn’t we just have a solar eclipse?
Last October’s stunning “ring of fire” show was called an annular solar eclipse, which occurs when the moon passes directly in front of the sun but is at or near its farthest point from Earth, and is therefore not large enough to completely cover the sun’s face. You can Nasa’s guide to the different types of eclipses here.
Why is this one special?
An estimated 31.6 million people, nearly three times as many as in 2017, live in the path of totality – which is longer, and also wider, than almost every other total eclipse before it, because the moon is closer to Earth and ‘ cast a wider shadow. . The time of totality in any given location is also longer. Seven years ago, the longest duration anywhere was two minutes and 42 seconds. On Monday, it will be four minutes and 28 seconds in Torreón, Mexico, while almost every place along the way can expect between three and a half to four minutes of totality.
How can I watch it?
If you live anywhere in the path of totality, or can travel there, congratulations, you have a front row seat. Just remember you need eclipse glasses (more on that in a minute) to look up at all times except the few minutes of total eclipse. But everyone in North America outside of the road should be able to see at least a partial eclipse of varying percentages, and Nasa will live stream the entire event here. Here’s the caveat: longer-range weather forecasts are required rain and clouds Monday in many areas of the southern and central US, so the best viewing may be in the east.
And here is Nasa’s Eclipse Explorerwhere you can enter any US address or zip code to find out what will be visible from that location.
What can I expect to see?
You can find Nasa’s guide to the stages of a total solar eclipse here. First contact is when the moon’s outer edge first touches the sun, creating the beginning of a partial eclipse and a crescent sun that diminishes in size to totality (second contact). In the moments before totality (in order) look for shadow bands, Baily’s Beads and a diamond ring, three of the most memorable stages of a total eclipse.
Shadow bands, say Nasa, are fast-moving, long, dark bands separated by white spaces that can be seen on the sides of buildings or the ground just before totality; Baily’s Beads are ephemeral rays of light from the sun streaming through the valleys along the moon’s horizon, giving way to the diamond ring effect, the last, single spot of bright light immediately before the end of any direct sunlight.
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The sun’s corona, the outer part of its atmosphere, can only be seen during the total part of the eclipse, then, after totality, the same effects come in reverse. For most locations, the partial eclipse phase lasts 70-80 minutes, according to Nasa.
How do I watch safely?
To look directly at the eclipse, you need special eclipse glasses. Regular sunglasses, frosted or dark glass, or any other method that lacks the necessary eye protection just won’t cut it. Nasa’s must-read blackout safety guide on the subject says: “Viewing any part of the bright sun through a camera lens, binoculars, or telescope without a special-purpose solar filter attached over the front of the optic will immediately cause serious eye injury.” Don’t do what Donald Trump did in 2017.
Many stores, businesses, schools and libraries still offer glasses for free or at low cost (Google is your friend here), but you need to make sure they are safety rated. The American Astronomical Society warned this last month unsafe fakes and counterfeits circulate, and has published a handy list of suppliers of safe solar viewers and filters (certified ISO 12312-2 compliant).
Experts advise against taking pictures of the eclipse with a cell phone (unless protected by a solar filter) because it can damage the camera. Nasa have thoughts here.
What if I don’t have eclipse glasses?
You can make a pinhole projector by following the steps in this video, courtesy of Nasa’s Goddard Space Flight Center. Another simpler method is to use anything with a small hole, such as a kitchen colander, to project an image onto the ground. And remember that many places around the country, like science centers and zoos, will host special eclipse events so you can watch the action safely.
