ArcGIS Pro

Totally Eclipsed

On April 8th 2024 parts of the United States will experience a total eclipse. This occurs where the moon crosses the path of the sun, blocking the sun on earth for a short while. The shadow created by the alignment of the sun and moon plunges those in the ‘path of totality’ into darkness. At distances away from the path of totality a partial eclipse can be observed with diminishing amounts of obscuration of the sun.

In this blog I introduce a new map of the total eclipse to help you prepare for this rare event. While most maps show the path of totality, and the times that you can expect to see the maximum amount of obscuration of the sun I wanted to go further, and create a map that actually illustrates precisely what you will expect to see (assuming cloud-free cover) on April 8th. I took the new symbol style I previously documented and developed ideas I’d used when creating a map of the annular eclipse in October 2023. Both the moonpies style I use, and that previous map can be downloaded from my previous blog.

So, here’s the new map, and if you want to skip the short discussion on the value of critique that I’m about to document then just go right ahead and download a hi-res PDF of it here.

Map of the US Total Eclipse, April 8 2024

There were several design ideas or motifs I wanted to use on the map to evoke a particular feeling. We are naturally curious about what our own place or situation is like so a map of the general path of an eclipse across a vast continent only goes so far.

By creating a grid of small symbol sets of the sun, and the moon’s position at the time of maximum obscuration the map helps people identify how the eclipse will appear where they are, not just where someone else is. That required a fair bit of maths to figure out the moon’s obscuration (as a percentage) and position relative to the centre of the sun (as a symbol rotation and offset). These will all be discussed another day but it’s all achieved using attribute driven symbology in ArcGIS Pro. The result is 1,500 small vignettes of the sun and moon that are all different and location specific.

I added an overlay of parallel buffer zones with a continuous gradient fill from darker (in the path of totality) to lighter the farther away you go. This was to accentuate the idea of the darkness experienced during totality, and how the effect is less pronounced with distance. There’s timelines that traverse the map showing the times that maximum obscuration will be reached on April 8th.

So the map functions to give you a way to determine how much of the sun will be obscured where you are, the position of the moon relative to the sun, and what time to go take a look (using solar viewing glasses!!!). The rest of the map contains the usual marginalia – a title, a neatline (using text rather than an actual line), an explanatory diagram of what an eclipse involves, a small globe showing the transit of the eclipse, an illustration of obscuration percentages, some explanatory text, and labels to give a sense of the geography of the United States across an otherwise abstract backdrop.

I created my map, spent a good while scouring it for errors and was generally pretty pleased with it. And at that point I could have unleashed it and sat back. Instead, I paused, and I sent it to a few of my colleagues for a review, sometimes called a critique. The whole purpose of this was to get eyes on the map before it gets published. Are there any obvious errors? Is the purpose, and messaging of the map clear. Is the symbology and graphical approach obvious, and does it fit the map? Is there anything missing that might improve the map? Are there superfluous elements that can be deleted? In simple terms…could a range of people understand what the map was showing!

Here’s that first draft of the map:

A first draft of the eclipse map

And whilst at first glance the draft and final map might look pretty similar, here’s a range of comments I received back, in no particular order:

Now, I will admit that my reviewers were on the whole very complimentary of the map and their comments and advice were really just about offering suggestions on things I might try. Critique is important in figuring out if your map is the best version it can be for the intended purpose so giving these comments fair consideration is a critical part of the work on the map. Often, other people bring different, or better ideas to the table. So even if you’re really experienced I’d always recommend you pause before publishing a map, and just see what others think of it. Take a deep breath and be prepared for comments that might be across a whole spectrum from overly complimentary to pretty damning!

Let’s, then, consider some of these and what I did with them.

Labels – I was hesitant to use the same font for the city labels as the rest of the map. I just didn’t think they would be legible enough. But I tried it, adjusted the sizing, and the drop shadow so the combination of light text with a dark shadow would work across different light-dark backgrounds. It seemed to work so I kept it.

City label points – I hadn’t included them originally to avoid too much additional symbology clashing with the sun and moon graphics. I also almost always use round point symbols for cities – and that would have clashed. But what if I use small squares, and combine a larger white square with a smaller internal black square? It works. It’s sufficiently different to the main graphics to not get in the way, and it certainly helps anchor the city labels themselves. I experimented with tilting them and adding shadows and locational specific angles but it got too convoluted and unnecessary. Know when to stop!

Path of totality strip – I darkened it. And it helped create a better range of depth of colour across the map.

Inset globes – I changed the basemap, and I made the obscuration buffers match the main map. Boom!

Title text – Simply by changing the glow effect from a black that was intended to fade into the background to an orange glow (one might almost call it a firefly look and feel) makes the title seem far more grounded in the overall map design.

Neatline text – A simple change from grey to yellow to match the map palette took seconds and makes a huge difference.

Timeline lines – Changed from black dashes on a white solid line to white dashes on a black solid line with a smidgen of transparency. Brilliant! Much better.

Sunglasses graphic – Agreed. Superfluous and a little contrived. Deleted.

Neatline and legend text typos – Errors! There always are, and you’ll never ever spot them all yourself. Corrected. Phew!!!

Typographical improvements – All implemented, and they clarify and read much better.

 

Many of these suggestions might seem pretty small, even irrelevant, but these marginal gains all add up to a much better overall composition even if I chose not to implement them all. And in the process of making the adjustments there were a few other small changes I made like curving the subtitle text in the title, and adding ‘United States’. It may be obvious where the map is, but possibly not to everyone so I thought it was important. Most of the map labels needed slight adjustments given the updated font, and to avoid the brighter parts of the background where possible. The ‘Path of Totality’ text was modified to increase the letterspacing so it spread a little more across the full path on the map, and adjusted so that the individual letters avoided clashes with other map detail as far as possible. I added an atmospheric hazy glow around the globe insets. Because…why not! And I made a lot of the text a very light grey (5% black) rather than pure white. In fact, on most maps I make I rarely use solid black or white as they can be a bit harsh. Softening the colours even a little helps tie everything together.

And with that, I published my map, with grateful thanks to my reviewers who gave their time and expertise to help make the map better. I hope that this short discussion of their comments, and how I implemented them, helps illustrate the value of map critique. And I hope the map helps you prepare for the total eclipse on April 8th.

You can download a hi-res copy of the map here. And don’t forget your solar viewing glasses!!!

Happy Mapping!

About the author

Ken is an academic cartographer and geographer from the UK, and since 2011 he teaches, talks and writes about cartography, and makes maps to demonstrate map design at Esri. He considers himself a professional 'cartonerd', educated with a Bachelors in cartography and a PhD in GIS and health geography, and over 30 years experience designing curricula, and teaching map design and GIS. He has presented and published an awful lot and is in demand as a panelist and keynote. He blogs (cartoblography.com), tweets (@kennethfield), is past Editor of The Cartographic Journal (2005–2014), and past Chair of the ICA Map Design Commission (mapdesign.icaci.org 2010-2018). He’s won a few awards for maps, pedagogy and kitchen tile designs. He is author of the best-selling books 'Cartography.' and 'Thematic Mapping' and leads the Esri MOOC on cartography which has been taken by over 200,000 students interested in making better maps. He snowboards, plays drums, builds Lego and supports Nottingham Forest.

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