The 1781 map made by Mademoiselle de St Laurent showing the path of the moon’s shadow across the Americas is remarkable.
You’ll want to keep it in mind as you block off the late afternoon and evening of May 20 on your calendar for what I’m thinking of as “our solar eclipse.”
The coming “annular” solar eclipse is one of those natural spectacles you won’t want to miss, perhaps the most remarkable celestial spectacle you’ll have the luck to witness firsthand. As seen from Albuquerque, the moon for more than 4 minutes will have passed completely in front of the sun, leaving only a tiny ring of fire, the “annulus.”
The eclipse will be visible over a large area, but because of Albuquerque’s location right in the bull’s-eye of maximum darkness (along with freeways that make it easy to move if clouds are blocking your view), we’re becoming global eclipse central for the international community of eclipse chasers. The peak of the action comes at 7:33 p.m.
What’s remarkable about the St Laurent map, which Santa Fe-area cartographer and eclipse map aficionado Michael Zeiler calls one of the favorites in his collection, is what it tells us about the role of eclipses in the trajectory of scientific history.
In 1781, astronomers were able to predict with great precision the path of the moon’s shadow in its sweep S-curve from the Pacific Ocean, across Central America and the Atlantic to the coast of Africa. But for the landforms that covered Earth’s surface, St Laurent still faced gaps in our knowledge. While she knew the path of the eclipse, she followed a mapmaker’s convention of the day by leaving much of the northwest coast of North America blank.
At the time, we knew more about the heavens than the surface of our own planet.
While European explorers were only beginning to fumble around the planet making their maps of Earth’s surface, a pair of early modern scientists, Demark’s Tycho Brahe and Johannes Kepler of Germany, had pretty much nailed down the basics of celestial motion by the 1600s.
As a young man, Brahe was a bit of a scientific scamp, sneaking out at night to make astronomical observations while the rich uncle who was supporting him thought he was studying law. What he learned and saw eventually earned the attention of the king of Denmark, who funded him to build what is often called the first modern astronomical observatory.
With the data Brahe collected on the motions of the sun, moon and planets, Kepler developed a set of basic mathematical principles about how the heavens work that still hold up reasonably well today. There have been many refinements since, but with Brahe’s data and Kepler’s mathematical underpinnings, it finally became possible to predict with certainty when the moon would pass in front of the sun and where on Earth’s surface it would cast its shadow — an eclipse.
By the early 1700s, cartographers were producing eclipse maps, showing where the eclipses would fall. By the early 1800s, Prussian scientist Friedrich Bessel came up with a refined mathematical tool kit that for predicting eclipse paths that “was so successful that it remains today as the most powerful technique,” according to a NASA history.
“It is still the current standard of eclipse prediction and mapping,” said Zeiler, who uses data from colleagues using Bessel’s methods to make his own, beautiful wall-sized eclipse maps.
So keep in mind as you’re out enjoying the May 20 eclipse that you are participating in something that traces its lineage directly to some of the first of the modern scientists.
As the date gets close, the Journal will be publishing a more detailed guide to safely watching the eclipse, but for today keep this very important point in mind: Do not look directly at the sun. Even though the moon’s blotting out much of its brightness, what remains can damage your eyes.
Quick tips include No. 14 welder’s glass or specially designed eclipse-watching glasses (available online at astronomerswithoutborders.org). Regular sunglasses are insufficient.
There is are a growing list of local organizations holding eclipse-watching events, including the New Mexico Museum of Natural History and Science, the Albuquerque Balloon Museum, the University of New Mexico Observatory and Petroglyph National Monument.
I’m collecting as full a list as I can of the eclipse events, so if you know of one or if your group or institution is planning one, email me at the address below.
UpFront is a daily front-page opinion column. Comment directly to John Fleck at 823-3916 or firstname.lastname@example.org. Go to www.abqjournal.com/letters/new to submit a letter to the editor.
— This article appeared on page A1 of the Albuquerque Journal