Thousand Year Canon of Solar Eclipses

An important new book has just been published by the leading authority on eclipse predictions, Fred Espenak. The significance of this book is its increased accuracy based on a new JPL ephemeris and the organized presentation of essential eclipse data. 

Fred previously published the Fifty Year Canon of Solar Eclipses: 1986–2035 and Fifty Year Canon of Lunar Eclipses: 1986–2035, co-authored Totality - Eclipses of the Sun  with Mark Littmann and Ken Willcox, and co-authored the Five Millennium Canon of Solar Eclipses: -1999 to +3000 with Jean Meeus. Fred is well known in the eclipse community for the essential eclipse bulletins produced during his tenure at the NASA Goddard Space Flight Center with maps and weather analysis by Jay Anderson. 

From the book description:

"The Thousand Year Canon of Solar Eclipses 1501 to 2500 - Color Edition contains maps and data for each of the 2,389 solar eclipses occurring over the ten-century period centered on the present era. The eclipse predictions are based on the Jet Propulsion Lab's DE406 — a computer ephemeris used for calculating high precision coordinates of the Sun and Moon for thousands of years into the past and future.

Section 1 of the Canon presents fundamental concepts including eclipse classification and the visual appearance of each type of eclipse. Section 2 discusses the eclipse predictions, the constants used and Delta T. A statistical analysis of eclipse frequency, extremes in eclipse magnitude, greatest central duration and quincena combinations are covered in Section 3. A concise explanation of the data contained in the solar eclipse catalog (Appendix A) appears in Section 4 while Section 5 offers a complete description of information presented in each of the solar eclipse maps (Appendix B).

The primary content of the Thousand Year Canon resides in the two appendices. Appendix A is a comprehensive catalog listing the essential characteristics of each eclipse. These include the calendar date and time of greatest eclipse, Delta T, lunation number, Saros series number, gamma, eclipse magnitude, geographic coordinates of greatest eclipse, Sun's altitude and azimuth, central path width and central line duration. Appendix B is an atlas of maps depicting the geographic regions of visibility of each eclipse. The zones of partial eclipse and central eclipse (if applicable) are plotted on an orthographic projection map of Earth. The 2,389 maps are arranged twelve to a page at an image scale permitting the assessment of eclipse visibility from any location on Earth. Other data on each map include the eclipse type, calendar date and time of greatest eclipse, Saros series number, lunar node, Delta T, gamma, Sun's altitude, and central eclipse duration or eclipse magnitude.

The key feature of the Color Edition is, of course, the fact that all the eclipse maps in Appendix B are reproduced in color. Since each of the curves making up an eclipse are color coded, this greatly aids in interpreting the maps. For example, the central path of total eclipses is plotted in BLUE while annular eclipses are RED."

This volume will no doubt become a well-worn addition to the bookshelf of eclipse enthusiasts.

Solar Eclipse Conference 2014

In two months, eclipse chasers from around the world will gather at Cloudcroft, New Mexico for the fifth Solar Eclipse Conference on October 25 and 26. Many of the leading experts on solar eclipses and solar physics will gather for an exciting program of talks on every aspect of eclipse observation and science. Conference registration is closing soon so if you are passionate about eclipses, considering attending this event.

There are also pre-conference sessions on August 23 and 24 at the nearby National Solar Observatory at Sacramento Peak. These dates coincide with a partial solar eclipse on October 23rd. 

From the conference organizer Patrick Poitevin: 

"Over the last few decades, there have been dramatic changes in solar eclipse traveling. Solar Eclipse specialists meet most of the time in the shadow of the Moon. Solar Eclipse meetings out of totality are rare, or are mainly focused on solar physics. The Solar Eclipse Mailing List and before the Solar Eclipse Newsletter has been successful as a vehicle in bringing together solar eclipse enthusiast, professionals and amateurs alike. Because there was no central eclipse in 2000 we had been presented with a perfect opportunity for an International Solar Eclipse Conference.

We had had this project in mind for some time, but mainly due to planning eclipse travels it has been put on hold. The aim of the conferences is to bring together professionals and amateurs, addicts, enthusiasts, and chasers, as with the mailing list and the newsletter, sharing information, knowledge, and experience. For the same reason we organized an international Solar Eclipse Conferences in 2004 and 2007.

Two days of lectures are given in each of the disciplines: predictions, mathematics, solar physics, weather forecasting, eye safety, diameter measuring, edge and central, and ancient eclipse research. Of course the latest and forthcoming solar eclipses should be great topics of discussion, along with the once-in-a-lifetime Venus Transit. Friday evening is a social event with reception and informal meetings. And where possible the conferences is combined with a lunar eclipse, partial solar eclipse and a visit to a solar observatory."

The Great European Eclipse of 1999

Fifteen years ago today, Europe experienced a total solar eclipse with broad similarities to the 2017 American eclipse. It traversed the continent from the northwest to its southeast, it was roughly the same duration (a little more than 2 minutes), and millions of people were able to see this spectacle. 

This is the BBC presentation from that day. Here are some more video links:

France: https://vimeo.com/87308913

France: https://vimeo.com/35620483

Hungary: https://vimeo.com/18322536

Iran: https://vimeo.com/62956118

I remember that day well. My intended place for observation was in the place of my birth in southern Germany. But on the previous day, the weather forecast for Germany was grim. So I dashed to Austria and drove and drove to escape the cloudy weather. 10 minutes before totality, I finally stopped in a farmer's field very close to the Austrian-Hungarian border and saw the breathtaking corona.

Each total solar eclipse is different and the vision of each is seared in your memory. My impression of this symmetric corona was that it appeared as a ghostly sunflower in the sky.

Darkness at Noon, 1806

I am lucky to have in my collection Darkness at Noon, an early pamphlet on the June 16, 1806 total solar eclipse which passed over New England. This remarkable document by Andrew Newell narrates the theory of eclipses, describes local circumstances for the 1806 eclipse, tells the reader how to view the eclipse, and dispels superstitions surrounding eclipses.

This pamphlet is scanned in its entirety in the gallery. 

From the introduction:

"The Science of Astronomy, in all ages, has been a subject of superlative excellence. By its discoveries, knowledge has been diffused in rich variety over the face of the civilized world; and imagination has found a field where it can rove without restraint of limitation."

"The discoveries which have been made in this science within the last three centuries have exceeded the warmest expectations of human reason; for the mind, which was once limited to the narrow confines of a little earth, is now able by the telescope to travel space, and make excursions into the distant regions of the heavens; and a prospect is now opened to us, as wonderful as it is infinite."

Dubious advice for viewing the eclipse (by present standards) is given on page 12.

Pages 13 through 29 give a competent, if verbose, narrative on the causes of eclipses.

Page 30 begins with the counterintuitive but correct notion that "Eclipses of the sun are more frequent than those of the moon; but, we have more visible eclipses of the moon than of the sun, because a lunar eclipse is seen from all those places on the earth which are directed towards her"

Page 32 gives a list of eclipses visible in New England from 1778 to 1811.

Pages 35 and 36 tabulate prominent solar eclipses from 431 BCE to 1438 CE.

As I look at this pamphlet again, it strikes me that the purpose of this 1806 pamphlet are identical to the goals of greatamericaneclipse.com. I will endeavor to do as well.

An epic canon of eclipses

One of the 160 maps in the Canon der Finsternisse showing eclipses from 2008 to 2030

Among eclipse cognoscenti, the Canon der Finsternisse (Canon of eclipses) by Theodor von Oppolzer (1841-1846) stands alone in the pre-computer era as the epic compendium of eclipse calculations and maps spanning over three millenia. 

Theodor von Oppolzer was a mathematician, geodesist, and astronomer and published many papers with computations for orbital elements of asteroids and comets. Oppolzer observed the solar eclipse of 1868 August 18 and was inspired by this event to begin the calculations of solar eclipses which culminated in his Canon nearly 20 years later. Oppolzer organized a group of ten human computers to divide the task of calculating 8000 solar eclipses and 5200 lunar eclipses. For each solar eclipse, points were calculated for the begin, end, and mid-point of eclipse and circular arcs were drawn between the three points, resulting in considerable inaccuracies in the geographic locations of eclipse paths.  

Within the Canon, the circumstances of the solar eclipses were summarized in a set of 160 tables with correlating maps. Each table and map represents a set of 50 successive solar eclipses. The fact that each table and map contains exactly 50 eclipses explains why they span irregular intervals of about 20 years, plus or minus a year or two.

Sadly, Oppolzer did not live to see the completion of his opus; he died the year before its publication. He is reported to have inspected the final proof-sheets of the Canon in the hours before his death at the age of 45.

The original Canon der Finsternisse is exceedingly rare and is found only within university or observatory libraries. In 1962, the Canon was reprinted by Dover Publications and translated into English by Donald Menzel and Owen Gingerich. I was fortunate to meet Owen Gingerich during the 2012 transit of Venus upon Mount Wilson, California and have his signature inside the front cover of my copy of the Dover edition.

An ancient eclipse computer

By Tilemahos Efthimiadis from Athens, Greece [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Probably the most astounding artifact from antiquity is the Antikythera Mechanism discovered in 1900 at an ancient shipwreck off the Greek island of Antikythera. This gearwork was dated to approximately 100 BCE and was quickly recognized as a remarkably advanced piece of ancient technology. This degree of sophisticated gear technology which was not attained again until the 14th century in western Europe.

Over the 20th century, many theories were developed to divine the purpose of this gearwork. In recent decades, considerable progress has been made by The Antikythera Mechanism Research Project and it's purpose is now clear: this mechanism was devised as a computer for the prediction of possible dates of solar and lunar eclipses.

A new research article Eclipse Prediction on the Ancient Greek Astronomical Calculating Machine Known as the Antikythera Mechanism has just been published by lead scientist Tony Freeth. From the abstract:

“The ancient Greek astronomical calculating machine, known as the Antikythera Mechanism, predicted eclipses, based on the 223-lunar month Saros cycle. Eclipses are indicated on a four-turn spiral Saros Dial by glyphs, which describe type and time of eclipse and include alphabetical index letters, referring to solar eclipse inscriptions.
...
The ancient Greeks built a machine that can predict, for many years ahead, not only eclipses but also a remarkable array of their characteristics, such as directions of obscuration, magnitude, colour, angular diameter of the Moon, relationship with the Moon’s node and eclipse time. It was not entirely accurate, but it was an astonishing achievement for its era.”

Three aspects of the Antikythera Mechanism are particularly striking;

• the advanced level of metal gear technology which arose in a Greek colony and was lost for 15 centuries,
• the sophisticated understanding of the motions of the Sun, Earth, and Moon by Greek astronomers which were applied to eclipse prediction, and
• the importance of solar and lunar eclipse predictions to ancient cultures.

The first eclipse map in the American Ephemeris

Eclipse map showing the extent of the partial solar eclipse over northeast North America and much of Asia. 

As this website is inaugurated, it's appropriate to recall the launch of the American Ephemeris and Nautical Almanac in 1855. Ephemerides had been published since antiquity with predictions for the motions of heavenly bodies and solar eclipses were always prominently documented, usually with maps.

With this map, the United States Naval Observatory (USNO) began publishing eclipse maps of each eclipse that occurred for the year of publication. This publication of eclipse maps continues to this day in the Astronomical Almanac jointly published by the USNO and Her Majesty's Nautical Almanac Office (of the United Kingdom).

One of the key missions of GreatAmericanEclipse.com is to continue this eclipse mapmaking heritage with the publication of detailed and informative maps of the 2017 total solar eclipse for the public. Eclipse maps are special due to their ephemeral nature; they are good for only one area at one specific moment in time! An eclipse map invites you to see the breathtaking sight of a total eclipse of the Sun.

You'll find this and many more historic and contemporary eclipse maps at the sister website of GreatAmericanEclipse.com, eclipse-maps.com