Like millions of other people, seeing the aurora borealis had long been on my list of travel goals. I was overjoyed eight years ago to finally experience the Northern Lights in Iceland after visits to Norway, Alaska and Iceland. Surprisingly, I was able to see the mesmerizing green and purple lights from the deck of my rental apartment in the heart of Reykjavik for three nights in a row in late September.

According to maps.com, there’s nothing boring about the aurora borealis. As charged particles from the Sun interact with Earth’s magnetic field, some of them travel along field lines and collide with other atoms in the magnetosphere. Excited by these collisions, the atoms release energy in the form of visible light. The molecular composition of the atmosphere and the altitude of these collisions can produce a vibrant array of greens, yellows, purples, and reds. It truly is a remarkable sight, and seeing an aurora is often considered a bucket list experience.

That’s exactly the case for Harry Kuril, a cartographer and outdoor enthusiast with a background in geophysics from Cambridge and MIT. But Kuril knows auroras are fleeting. Seeing these ephemeral whisps of light comes with no guarantee. In addition to the presence of charged particles waxing and waning with the solar wind, other environmental factors can enhance or impede one’s view of the night sky. To better his chances, Kuril turned to his experience as a cartographer.

Using data from NASA, NOAA, and others, Kuril first mapped the average energy flux to estimate the strength of the aurora for a given time range. He then mapped average cloud cover to determine the conditions that might be typical for the season. Finally, a map of light pollution helps filter out locations too washed out with artificial lighting. By combining all these data, Kuril produced a metric to identify which areas offered the best chance to see the aurora. This aurora score, once mapped, provides a chart to the areas with a strong aurora, clear skies, and low influence from the cities below.