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Planning Your Solar Eclipse Encounter with Cesium

Observing a total solar eclipse is a unique and powerful astronomical experience. The difference between 99% and 100% eclipse coverage is vast because the disc of the sun is so bright that even 1% of it blindingly outshines all of the stars in the sky. To truly block out all of the sun high in the sky is absolutely worth the effort to see in person at least once in a lifetime!

In the United States, after many decades with no total eclipse opportunities, a pair of chances finally arrived… and is almost behind us. The first came August 21, 2017. The second is just a few weeks away: April 8, 2024. After that it’ll be 21 years until the next chance to see a total solar eclipse in the continental US (August 12, 2045).

So… where to go? And how to set oneself up for success?

Tracing the path of totality in

Some years ago, as the 2017 eclipse approached, I wanted a tool to plan my first encounter with a total solar eclipse. So became, a Cesium-powered visualizer of total solar eclipse tracks across the surface of the Earth.

Line across North America showing the path of totality in the April 2024 solar eclipse

The versatility of the open source Cesium platform made the process of visualizing over 100 years of eclipses straightforward. Raw eclipse track data from NASA is scraped, parsed, and transmuted into CZML to be served up in a single-page web application. The full source for the application and data processing pipeline is available on GitHub.

Recent additions to include terrain support. This will come in especially handy in 2045 as the path of totality cuts right across the core of my lovely and mountainous home state, Colorado.

Shadow over mountainous terrain in Colorado showing path of totality in the April 2024 solar eclipse

Terrain in makes it easier to see areas that will be within the path of totality.

Another update is emulation of “bookmarkable” URLs much like other mapping web apps such as Google or Bing maps. The image above is no longer relegated to only a screenshot; see it live here. Changing the camera position updates the url with the current state of the camera and clock so one can return to (or share) the exact view of an eclipse event at a point in time and space.

Tips for a successful total solar eclipse encounter

Prepare to be mobile all day

You may need to outrun clouds. Know your routes along the path of totality in both directions. Expect lots of crowds and lots of traffic so keep your vehicle fueled up and filled with food, water, and anything else you may need for many hours spent on the road.

Know your forecast

I strongly recommend learning how to read the forecasts from That link is for Buffalo, NY, which is on the path of totality this coming April. These grids of colorful squares are a highly local and highly accurate rolling 48 hour picture of several atmospheric conditions that will affect visibility of anything in the sky, including cloud cover and air transparency. Be watching several observatories along the path from your target viewing location up to the day of the eclipse to get an idea of whether you may need to relocate.

Get your eclipse glasses now!

You’ll need eclipse glasses to look at the partially eclipsed sun, even 99%! A location experiencing three minutes of totality will also experience over an hour of partiality before and after. Inexpensive eclipse glasses are readily available from any general ecommerce website.

If you plan to witness the 2024 total solar eclipse I wish you clear skies and easy travel!

Now, I mentioned that the 2017 event was my first opportunity to see a total solar eclipse. At 35 years old I was able to also provide that first opportunity to my son, who wasn’t yet two. Now, at age seven, I’m thrilled he’ll have another chance to see one (that he’ll now be old enough to remember), especially because when the next umbral shadow of the moon passes over our corner of the planet he’ll be pushing thirty himself. And one of the best parts about chasing such an awe inspiring event is sharing the experience with loved ones by your side.

Carpe eclipsis!

This is a guest post by Christoph Clark, creator of - Sarah