Although there are two to five eclipses of the Sun every year, each eclipse is only visible from a limited region of the daylight side of Earth. No single place or city will see every eclipse. In fact, several years may pass between the appearance of two eclipses from any one place. Furthermore, most eclipses appear partial from a single location even if the event is classified as total or annular. This apparent contradiction can be explained because the path of a total (or annular) eclipse is quite narrow and covers less than 1% of the Earth's surface. In comparison, a partial eclipse is visible is much larger region which may include over half of the day-side hemisphere of Earth. Eclipses for Beginners examines the geometry of solar eclipses in greater detail. Please note that extreme care must be taken when viewing a solar eclipse.

To determine whether an eclipse is visible from a given city is a formidable computation. It requires the evaluation of hundreds of trigonometric equations to predict the exact positions of the Sun and Moon as a function of time. An even more arduous problem is to ascertain when either the last or next total eclipse is visible from a city. To answer this question, one must calculate the circumstances of every single solar eclipse over the time period of interest. On the average, about 375 years elapse between the appearance of two total eclipses from the same place. But the interval can sometimes be much longer!

The digital computer (with appropriate software) is perfectly suited to addressing a number of eclipse questions including:

"How often is an eclipse visible from Chicago ?"
"When was the last partial (or annular, or total) eclipse visible from Chicago ?"
"When is the next partial (or annular, or total) eclipse visible from Chicago ?"

The table below summarizes the types and numbers of eclipses visible each century from Chicago during the period 0001 CE to 3000 CE . The last two columns list the years in which annular and total eclipses are visible from the city. During this interval, 8 annular eclipses are visible from Chicago ( 0451, 0608, 0716, 0881, 1008, 1125, 2614 and 2851 ). For the same period, 11 total eclipses are visible from Chicago ( 0102, 0192, 0556, 0957, 1205*, 1379*, 1558, 1806*, 2099*, 2205 and 2672 ). Annular and total eclipses are extraordinarily uncommon events when viewed from a single place. On average, an annular eclipse is seen once every 224 years, while a total eclipse is seen once every 375 years. However, there can be significant variations in these averages.

BCE (Before Common Era) and CE (Common Era) are secular alternatives for the terms BC and AD, respectively. For more information, see Year Dating Conventions.

BCE (Before Common Era) and CE (Common Era) are secular alternatives for the terms BC and AD, respectively. For more information, see Year Dating Conventions.

The following catalogs present circumstances for every solar eclipse visible from Chicago during the period 0001 CE to 3000 CE . Each catalog is a separate web page which covers 1,000 years. For convenience, all dates and times are given in local standard time (= GMT - 6.0) . In addition to the date and the type of eclipse visible from Chicago , the local times for the beginning, maximum and end of the eclipse are given. For maximum eclipse, each catalog lists the Sun's altitude and azimuth as well as the magnitude (fraction of Sun's diameter covered) and obscuration (fraction of Sun's area covered). The number of years elapsed since the previous eclipse visible from Chicago is listed next. If the eclipse is annular or total from some portion of the Earth's surface, then the distance (km) from Chicago to the center and edge of the eclipse path are provided.

Special notes (last column) call attention to major partial eclipses (magnitude ≥ 0.75 ), or occasions when a total or annular eclipse path passes within 500 km of Chicago . Finally, if the eclipse is actually annular or total from Chicago , then the duration of annularity or totality is given. For a complete description of each item in the catalogs, please see Key to Solar Eclipse Viewing Circumstances. For a basic explanation on why solar eclipses occur, see Eclipses for Beginners.

Two additional catalogs are available to investigate solar eclipses visible from Chicago during the period 2001 CE to 3000 CE . The first catalog lists the local circumstances (times, magnitude, etc.) for major eclipses (magnitude greater than 0.75 , and nearby annular and total eclipses). The second catalog focuses exclusively on annular and total eclipses seen from within a distance of 15 km of the center of Chicago . The catalogs should prove useful for historical research or for planning future observations. They can be accessed via the following links.

Eclipse Predictions & WebMaster: Fred Espenak e-mail: espenak@gsfc.nasa.gov Planetary Systems Branch - Code 693 NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 USA