NASA’s More Accurate Eclipse Maps

A map showing the umbra (the Moon’s central shadow) as it passes over Cleveland at 3:15 p.m. local time during the April 8, 2024, total solar eclipse. (NASA SVS/Ernie Wright and Michaela Garrison)
NASA SVS/Ernie Wright and Michaela Garrison

For the 2017 solar eclipse, NASA published eclipse maps that took the irregular umbral shadow of the moon into account: the umbra is neither circular nor oval but irregular—more polygonal—thanks to the uneven topography and elevation of both the moon and the earth. Not accounting for that introduces errors into the map that could make the difference between observing a partial rather than a total eclipse. The process behind those more accurate eclipse maps, which involves computer processing of both lunar and terrestrial elevation models, has now been published in The Astrophysical Journal. [Bad Astronomy]

xkcd: ‘Every Eclipse Path Map’

An xkcd cartoon about eclipse path maps.
Randall Munroe, “Every Eclipse Path Map,” xkcd, 17 Apr 2024.

Looks like we’re not quite done with eclipse maps, especially the whimsical sort, and it’s not at all invalid for xckd to have (what is probably going to be) the last word on the subject (at least for a while), with this fictional map showing the fictional path of a fictional eclipse over a fictional landscape, with rueful descriptions of fictional places where trying to see the fictional eclipse will come to a bad end for the fictional observers. (And you thought it was bad you got clouds.)

New Eclipse Map Claims Narrower Path of Totality

CNN: “New map calculations have raised some concerns that the path of totality—where it’s possible to see the moon completely block out the sun—is slightly narrower than NASA calculated. That means some cities on the edge of the route that were expecting to experience a second or two of total darkness might be left out.” The calculations were done by John Irwin, whose revised map can be found here. This page has the technical details, while Jamie Carter explains the implications: if Irwin’s correct, we’re talking about a literal edge case of a few hundred metres. Go further into the path of totality!

Previously: Cloud Cover Risk During the 2024 Solar Eclipse; Mapping Two Solar Eclipses.

Cloud Cover Risk During the 2024 Solar Eclipse

Eclipses aren’t any fun if you travel to go see one and it’s cloudy. I’ve been debating with myself what to do about next month’s total solar eclipse: the path of totality is a couple hours’ drive away and therefore manageable, but from what I’ve gathered the odds of clear skies aren’t great. These odds are based not on weather forecasts—still too early for that—but on historical data. For example, NASA Earth Observatory’s map, above, shows the average of the past 20 years of cloud cover across North America’s eclipse track on the day of the eclipse (April 8). Want more detail? Like, a lot more? See this incredibly detailed analysis from Eclipsophile’s Jay Anderson; I believe he’s a former meteorologist, and boy does it show in this piece. See also this Weather Underground article from last January, plus coverage from CBC News.

Previously: Mapping Two Solar Eclipses.

Mapping Two Solar Eclipses

Map of the path of the annular eclipse on October 14, 2023, across the American Southwest.
Michael Zeiler, GreatAmericanEclipse.com

Two upcoming solar eclipses in North America—the annular eclipse on October 14, and the total eclipse on April 8, 2024—are the subject of numerous eclipse maps that track the path of totality and its duration along that path.

NASA’s Solar Eclipse Explorer currently focuses on this month’s annular eclipse, with paths of the 2017 and 2024 eclipse for comparison. [Maps Mania]

The Eclipse Company has separate maps for this month’s annular eclipse and next April’s total eclipse: these maps include data for locations along the path, including time, duration, the sun’s altitude and chance of clouds based on historical weather data. [PetaPixel]

The last time I went looking for eclipse maps, back in 2017, there was a website called GreatAmericanEclipse.com, which was the most recent of the websites showcasing the eclipse maps of Michael Zeiler. It’s still very much a going concern, with maps covering North America, individual U.S. states, and detailed maps of the path itself. These are static maps rather than the above interactive maps, but there are a lot of them, and not just for this month’s annular and next year’s total eclipse: there’s a fair bit of historical (and future!) eclipse maps there too.

Update 10:20 PM: Andy Woodruff’s scrolling map of the 2024 eclipse.

Previously: An Almost-Too-Late Roundup of Historical and Unusual Eclipse Maps; Mapping the August 2017 Solar Eclipse; Another Solar Eclipse Website; Michael Zeiler’s Solar Eclipse Map Website; Eclipse Maps.

An Almost-Too-Late Roundup of Historical and Unusual Eclipse Maps

I meant to post this before today’s solar eclipse, but I spent a good chunk of the past few days dealing with basic site maintenance; during the eclipse itself I was, well, observing and photographing it. But while the iron may not be as red-hot as it was even eight hours ago, it’s still glowing a bit, so how about I clear out some bookmarks:

Eclipse maps that pinpoint the zone of totality date back to the eighteenth century. Atlas Obscura looks at those early eclipse maps, notably those from Edmond Halley.

In the runup to the eclipse there have been some seriously weird and quirky eclipse maps, many of which correlating the path of the eclipse to utterly unrelated things. The first one I saw was this one: the path of the eclipse versus bigfoot sightings.

There have been others. Many others, to the point of absurdity. Maps on the Web has been collecting these maps over the past few weeks, and All Over the Map’s roundup of eclipse maps features them as well.

Earlier this month, the Washington Post’s Wonkblog noted the eerie correlation between Google searches about the eclipse and the path of the eclipse itself:

Washington Post

Finally, people were watching traffic maps to track the number of people travelling to watch the eclipse. Apparently eclipse-related traffic congestion was a thing. (Here’s Michael Zeiler’s forecast, based on population statistics.)

Mapping the August 2017 Solar Eclipse

Drive times to the centerline of the August 21, 2017 total solar eclipse
Michael Zeiler, GreatAmericanEclipse.com

Eclipse maps—maps that show the path of solar eclipses across the surface of the Earth—are very much a thing. As I wrote in my first blog post about eclipse maps back in 2010, “These maps are vital to eclipse chasers, who spend vast sums travelling to places where they can see one, and those slightly less insane who nevertheless are interested in when the next one comes around.” Eclipse chasers are already getting ready for next month’s solar eclipse, which transects the continental United States on 21 August, and of course there are lots of maps.

Michael Zeiler, whose website about solar eclipse maps, coincidentally called Eclipse-Maps.com, I told you about in 2011, has launched a separate website dedicated to next month’s eclipse, called (wait for it) GreatAmericanEclipse.com.  There are eclipse maps for every state the path passes through, various maps presenting additional information, and a 10-foot-long strip map of the path of totality.

But knowing an eclipse’s path isn’t always enough. There’s nothing worse than spending a fortune to get to an eclipse-viewing spot only to discover it’s clouded over. You can’t predict the skies far enough in advance, but you can factor in the likelihood that skies will be clear or cloudy for a given location, based on historical weather data. That’s what NOAA’s eclipse cloudiness maps do. [GeoLounge]