Madison's Eclipse Drought
(February, 2001; revised July 2001)
by John Rummel
Solar eclipses, one of nature's rarest and most sought after observational prizes, are finicky and fickle things. A solar eclipse of some type happens about twice every year, yet over 99% of the humans alive today have never seen totality and never will.
The unique geometry of a solar eclipse requires that the moon's shadow cross only a narrow band Earth's surface during an eclipse. At its absolute widest, the path of an eclipse can never be more than 170 miles wide. Since over 70% of the Earth's surface is water, odds are the path of totality is over open ocean. When it does fall on land, odds are it's some remote, hostile, godforsaken patch of Earth that is sparsely inhabited and difficult to reach. Veteran eclipse chasers are undaunted however. Modern "umbraphiles" spend thousands of dollars and travel thousands of miles to get themselves under a few minutes of lunar shadow every few years.
This summer, eclipse chasers converged on Zambia, Zimbabwe, and Mozambique as the first total eclipse of the 3rd millennium passed over southern Africa. Civil war torn Angola was avoided by most shadow seekers. This solstice trek of the ambitious and highly motivated got me to thinking: when can us Madisonians next see an eclipse without leaving home? When is the next time totality will darken Dane County? A solar eclipse (partial, annular or total) happens on average twice each year somewhere in the world. When will Madison's number come up?
Russell, Dugan, and Stewart in their textbook "Astronomy" (vol. I, page 227) say that, on average, an eclipse will occur in a given location about every 360 years. Owen Gingerich elaborates on their reasoning on page 209 of his excellent compilation "The Great Copernicus Chase," and concludes, through much hedging owing to the Earth-sun-moon geometry, that the actual average is between 224 years and 427 years, depending on whether one is talking about annular or total eclipses (annular eclipses occur on average a bit more frequently), and the latitude of the location, which also affects frequency.
So I spent a few hours at my computer over several days, surfing the major eclipse web sites, and using some astronomy software simulators to search for candidate eclipses that would be visible from Madison. As with any such trek down trivia lane, I found some interesting facts, and a few astounding ones. I'm reasonably certain about the conclusions presented here, but as always, I welcome any informed critique, particularly if anyone knows of any previous attempts to pin down total eclipses visible from southern Wisconsin.
Let's start our journey first by reviewing the 20th century. In May 1994, a central annular eclipse crossed central Illinois and northern Indiana. The northern edge of the path was just south of Chicago, missing Madison by a good 150 miles. Back in 1954, a total solar eclipse crossed the twin cities in Minnesota, and passed through northwest Wisconsin. Another miss for Madison. January 24th, 1925, the path of totality grazed the northern tier of Wisconsin. This would have been a nice sight. Eclipse gazers in northeast Wisconsin would have been treated to the trio of Mercury, Venus, and Jupiter rising just before sunrise, and then the deeply eclipsed sun rising just minutes before totality. Known elsewhere as the "New York Winter Eclipse," because the path of totality went on to cross directly over much of Manhattan, Long Island, and Connecticut. Unfortunately, eclipse gazers in northern Wisconsin (and throughout the midwest) were completely clouded out that morning. Nobody saw a thing.
The 21st century is more promising. On August 17, 2017, a total eclipse will cross the United States from coast to coast. The path crosses southern Illinois - I'll be generous and call that a near miss for Madison. Seven years later, on April 8, 2024, totality again hits the midwest, cutting a path up through southern Illinois, Indiana, northwest Ohio, and New York). Just 21 years later, on August 12, 2045, yet another total eclipse path cuts across the US, passing through Oklahoma, Arkansas, Missouri, and Alabama. Three total eclipses, three misses for Madison.
Finally, a hit - sort of. On June 11, 2048, a central annular eclipse passes directly over Madison. It's not totality, but an annular is better than nothing.
Several other near misses round out the latter half of the 21st century, but Madison finally hits pay dirt on September 14, 2099, when a central total eclipse crosses directly over the southern badger state (see figure 1). Madison will be treated to just over 3 minutes of totality. Mark your calendars.
Figure 1: Path of the September 14, 2099 total solar eclipse across the state of Wisconsin. Lunar shadow crosses from west to east (left to right).
So Madisonians, born and not-yet-born, will have to wait 98 years for the next eclipse show on our home turf. To find out how long our current drought is though, we need to know when the last total eclipse was in Madison. Starting in the 19th century and working backwards, here's what we find:
On August 7, 1869, an eclipse crossed central Iowa, missing Wisconsin by just a few dozen miles. In September of 1838, an annular eclipse path missed Madison by about 50 miles, with the edge of the path crossing near West Allis. On September 17, 1811, an annular eclipse's path just barely grazed Madison, Appleton was near the centerline of this event. Prior to that event, we have to travel way back in time, to pre-settler days. In April of 1558, the edge of the path of totality missed the isthmus area that would become Madison three centuries later by just 70 miles. In June of 1451, another near miss to the east, with the path of totality crossing northeastern Wisconsin and Michigan.
The last time a total solar eclipse was visible in (pre) Madison was May 16, 1379. That makes our "drought period" 720 years long, a bit above the global average!
While looking at list after list of eclipse events, I found one circumstance that might be of interest to local eclipse enthusiasts. Though it lies nearly 20 generations in the future, I can't resist sketching out what might be southern Wisconsin's most incredible bunching of eclipses ever.
The show gets started with a total eclipse passing over Madison on June 17, 2672 (see figure 2). Six years later on August 9, 2678, an annular eclipse follows suit. Then, on June 8, 2681, another total eclipse, followed by a marginal call on November 10 2683. In this last event, the umbra reaches southern Wisconsin just as the sun sets over Madison, and it's debatable whether totality will be visible in Madison at all before the sun disappears below the horizon. Maybe Madison will have some skyscrapers by then that will allow future citizens to watch the show from the 50th floor, who knows? At any rate, all one has to do that day to ensure seeing totality is to travel down to Prairie Du Chein. The sunset from Madison that evening would be most unusual - the deeply eclipsed sun will drop toward the horizon, and just as it dips below and totality begins, the sky will darken dramatically for just over a minute, and then will suddenly brighten again as totality - now below the horizon - ends.
Figure 2: Four eclipse paths plotted over southern Wisconsin in the 27th century. Technically, only extreme southwest Wisconsin catches all four, but the proximity to Madison and the bunching in time were irresistible. In each case, the lunar shadow crosses from west to east (left to right).
Such three-fold repetitions of eclipses in one geographical area are not unheard of. In the April 2000 issue of Sky and Telescope, veteran eclipse calculator Jean Meeus writes of other occasions where one lucky geographic location is treated to 3, 4, or even 5 eclipses in a short span of time. Madison's 27th century event didn't make Meeus's cut because his list is made up of ten even more dramatic bunchings, all of which are under 8 years. However, only one of Meeus's top ten occurred over land.
Eclipses are wonderful and compelling events. Simulations and theoretical meanderings such as this article give a flavor for the wonderful rarity of this phenomenon and may encourage the reader to travel a bit for the opportunity to experience the shadow.
In preparing this article, I made heavy use of three excellent software programs: Voyager II for the Macintosh to find suitable eclipse candidates; Shinobu Takesako's excellent free Windows program, Emapwin to plot the shadow paths, and Starry Night Pro to simulate the local circumstances in Madison and other locations.
List of candidate eclipses for southern Wisconsin. Bold entries are central annular or central total eclipses close enough to Madison, WI to qualify as "hits" for the purposes of this article.
5/16/1379 (the last time the path of totality crossed the isthmus area that would become Madison, WI) 6/28/1451 (a near miss to the east, totality's path crossed NE Wisconsin and Michigan) 4/18/1558 (edge of path of totality missed area which would eventually become Madison by 70 miles) 6/16/1806 (edge of totality just barely grazes Chicago) 9/17/1811 (Annular path just barely grazed Madison, Appleton was near centerline) 9/18/1838 (Annular path just missed Madison by 50 or so miles (edge of path was near West Allis) 8/7/1869 (path of totality crossed central Iowa, missing Wisconsin by a few dozen miles) 1/24/1925 (path of totality grazed NE Wisconsin at sunrise) 6/30/1954 (path of totality crossed Minneapolis and passed through NW Wisconsin) 5/10/1994 (central annular crosses US from Oregon to S. Carolina. Centerline crosses southern IL, northern IN, edge of path just s of Chicago .898 in Madison) 8/17/2017 (totality path crosses US, closest to Madison, S. IL) 4/8/2024 (totality path cuts up though midwest, S. IL, IN, NW OH, NY) 8/12/2045 (totality path crosses US, OK, AR, MS, AL) 6/11/2048 (central annular crosses directly over Madison) 9/14/2099 (the next total solar eclipse shadow to cover Madison) 5/3/2106 (total solar misses Madison by less than 100 miles, .925 mag in Madison) 8/4/2111 (central annular path hits Madison) 7/14/2121 (annular, .854 in Madison, St. Louis on centerline) 10/26/2144 (total in Michigan's UP, .942 in Madison) 10/17/2153 (total in Waterloo IA and Peoria IL, .965 in Madison) 4/12/2154 (annular, .858 in Madison) 7/17/2205 (central total eclipse, northern edge barely grazes Madison) 2/21/2213 (central annular, just after sunrise in Madison) 5/26/2245 (central total, centerline from Sioux City to Minneapolis, miss Madison) 6/6/2263 (central total, centerline from Duluth to Marinette, miss Madison) 2/25/2343 (central total, northern edge of path grazes Peoria to Racine, miss Madison) 12/4/2355 (central annular hits Madison, centerline from Eau Claire to South Bend) 1/5/2410 (annular miss Madison, centerline from La Crosse to Marinette) 5/31/2421 (annular path grazes Madison, centerline Dubuque to Kenosha) 9/12/2444 (central total, south edge of path grazes Madison, centerline Fargo to Sheboygan) 6/3/2505 (central total, miss Madison, centerline De Moines to Detroit) 6/5/2551 (annular hits Madison, centerline De Moines-Madison-Sheboygan) 7/28/2614 (annular, northern edge grazes Madison, centerline Mankato to Dayton, OH) 6/17/2672 (total hits Madison, centerline De Moines to Green Bay) 8/9/2678 (annular hits Madison, centerline Sioux City to Sheboygan) 6/8/2681 (total hits Madison, centerline Lincoln NE to Green Bay) 11/10/2683 (total, sun sets in Madison just as totality begins) 7/1/2820 (annular, northern edge grazes Madison, centerline Iowa City to Janesville) 4/22/2851 (annular hits Madison, centerline Topeka Kansas to Sheboygan) 7/3/2866 (total miss Madison, centerline central Kansas to Ft. Wayne) 8/25/2929 (total miss Madison, centerline Rapid City to St. Louis)
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