by If we were to compare the “Great North American Solar Eclipse” on April 8th to other eclipses of the past century, where would it rank?
Actually, it would end up quite high on the list.
Over the last 100 years, from 1925 (inclusive) to 2024, the maximum total duration of the 75 solar eclipses we sampled (including null/hybrid and noncentral total eclipses) was 3 minutes 13 seconds. Incidentally, the maximum possible total duration of a total solar eclipse is 7 minutes 32.1 seconds, according to Jean Meeus, a Belgian Earth and planetary scientist who focuses on celestial mechanics.
Therefore, when a total solar eclipse reaches a period of more than 4 minutes it should definitely be considered an exceptional eclipse. Our upcoming total solar eclipse on April 8th will have a maximum duration of 4 minutes 28.2 seconds in north central Mexico. Among the 75 solar eclipses we sampled, 29 belong to the “Four Minute or Greater Club” and the April 8th eclipse is among the top 25% in terms of duration.
Related: Total solar eclipse 2024: Everything you need to know
Comparison of 100 years
Even more striking are the comparisons between totals crossing the borders of the United States during this 100-year time frame. These are listed in the table below.
Not including our 2024 eclipse that we kept separate, there are 14 eclipses in this particular survey. One of these (April 28, 1930) is a rare “hybrid” or total eclipse, in which the part of the eclipse path that produces a total (albeit brief) eclipse that passes over parts of five western states.
Comparing the characteristics of the April 8, 2024 eclipse with the 13th on our list, here is what we find:
Length: The total for the 14 United States eclipses is 1 minute 58 seconds. By this standard seven eclipses are “above average” and only two of 13 exceed the three-minute mark (March 7, 1970 and July 11, 1991). Excluding the April 8 eclipse, which produced a totality lasting 4 minutes 27 seconds for southern Texas, only the 1991 eclipse can last longer than four minutes.
maximum height: The higher the eclipsed sun up in the sky, the more likely it will be free of haze or clouds. The high for the upcoming event on April 8 is 69° (in south Texas). The average for the other 14 US eclipses puts the sun less than half as high in the sky at 32°. Four of the 13 have the sun more than halfway up (greater than 45°) in the sky. Note, however, that the second most favorable of the 14, that of April 28, 1930, was the annual total, with an altitude of an excellent 62°, with a “total” of only one second!
Maximum path width: When there is a total eclipse, the shadow of the moon cast on the surface of the Earth is in the shape of an ellipse. The height of the sun above the horizon controls how elliptical the shadow will be. The average of the 14 eclipses of the United States gives a path width of 89 miles. The upcoming eclipse on April 8 has a value of 108 miles in this category, but ranks fourth behind the eclipses of February 26, 1979, July 11, 1991 and July 22, 1990.
In fact, the 1979 eclipse was 83 miles wider than the 2024 eclipse.
It should be pointed out, however, that in the case of that eclipse from 1979, the sun was only at a maximum altitude of 24° (in northwestern North Dakota, near the town of Portal), and the umbral shadow hit the Earth rather obliquely . . As a result, the projected shape of the umbra on Earth was a very long oval measuring 83 by 191 miles along and across its path, respectively. Meanwhile, on April 8, over southern Texas, the sun’s total ecliptic altitude will be 69° — nearly three times higher than in 1979. So, rather than an elongated oval, the shape of the moon’s shadow in 2024 will be more circular. .
In another way, from North Dakota in 1979, at the center of totality, no one was located in the middle of the eclipse track more than 41.5 miles from the leading edge or edge of the umbra, on the other hand, on April 8. , at the center of totality in the middle of the eclipse track in southern Texas, an observer will be up to 54 miles from the leading edges and track of the umbral shadow.
Region of visibility: It seems that total solar eclipses tend to avoid large populated areas. While it is true that a few eclipses in our sample of 14 passed over large urban areas (NYC in 1925; Minneapolis 1954; Boston 1959), the total audience is made up mostly of smaller towns and communities. Even in the case of the 1970 eclipse parallel to the Atlantic shore, the shadow missed the heavily populated Northeast Corridor. The largest population center that experienced it overall was the Norfolk-Portsmouth, VA metropolitan area: 508,000. And the total number of people within the entire zone of totality is probably less than two million.
By contrast, the August 2017 total eclipse, whose path stretched from coast to coast, included an audience of 11 million people. But as impressive as that was, the upcoming eclipse on April 8 will pass over many metropolitan areas from Texas to northern New England, giving an estimated 32 million people the opportunity to see this spectacular spectacle first hand.
It is likely, therefore, that the upcoming eclipse on April 8 will represent the largest concentration of people ever immersed in the dark umbral shadow of the moon in the history of the United States!
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The past … and the near future: From everything we’ve observed so far, it’s clear that as far as the United States is concerned, the April 8, 2024 eclipse is pretty exceptional. In fact, there is only one other event with which we could make a reasonable comparison. That was the eclipse of June 16, 1806. On that day, the moon’s shadow swept across North America, crossing through the northern Midwest and continuing through New York State and New England. In terms of duration of totality, this eclipse was the best on the North American continent during the entire 19th century and would not be rivaled until the middle of the 21st century.
The total phase of this 1806 eclipse lasted 4 minutes 53 seconds in the vicinity of Marblehead, Massachusetts (northeast of Boston), and the mean totality with the sun near its highest point in the sky — 70° — occurred just half an hour earlier. . local noon.
And it will not be until the total solar eclipse on August 12, 2045, that the contiguous United States will, for the first time, experience a total eclipse of more than 6 minutes. The maximum expected total length for this unique event, near Port St. is 6 minutes 6 seconds. Lucie, Florida; the longest total in US history. Mark your calendars!
Until then, however, April 8, 2024 will be the best total solar eclipse for the United States between the years 1806 and 2045.
Joe Rao serves as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes about astronomy for Free natural history magazine,the The Farmers’ Almanac and other publications.
