This spring, the Northern Lights, a phenomenon that sees ethereal streamers of colored light pirouette across the night sky, made big appearances in the Lower 48, coloring the skies in places as far south as New Mexico.
For those who missed it, fear not, as you may have another chance to see the illusive aurora borealis in the Lower 48 tonight.
Scientists at the University of Alaska Fairbanks Geophysical Institute rank the probability of seeing the aurora borealis on a scale of zero to nine, which is called the Kp Index. The higher the number is, the better the probability the nighttime spectacle will occur. It also means that there’s a larger swath of the hemisphere that could potentially see the aurora.
For the night of September 18 and the morning of September 19, that number is six. That means the Northern Lights could be visible as far south as Oregon, Idaho, Wyoming, Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, and all of the Northeastern states. However, it’s more probable that if the dancing display happens in the continental United States, it will be seen in the northern parts of Washington, Montana, the Dakotas, Minnesota, Wisconsin, Michigan, and Maine.
What causes the Northern Lights—and when might we see them again?
The aurora borealis is caused when the sun shoots electrically charged protons and electrons toward the Earth during a solar storm. As those elements meet the Earth’s magnetic field, they’re attracted to the poles, where they excite and mix with the gases in our atmosphere. When the particles mix with oxygen, green and red lights appear; they glow blue and purple when they join with nitrogen. It’s the same process at work in neon signs.
Even if you don’t get to see the kaleidoscopic illuminations this time, your chances will only improve over the next few years. There’s an 11-year cycle that has historically predicted when the lights would be most visible. In the years closest to solar maximum (slated to happen in 2024), the shows are more frequent, energetic, and colorful (whereas they’re more lethargic in the years near solar minimum). They’re only going to get better and more frequent in the coming years, although they are also more active around the fall and spring equinoxes.
Tips for seeing the Northern Lights
It’s a good idea to download a mobile app, like Northern Light Aurora Forecast, to get a better idea of the likelihood of seeing the Northern Lights in your area. It can help spell out when the show might take place, if at all.
It’s worth noting that it’s only possible to see the Northern Lights when the sky is clear, and they’re not competing with ambient city lights. For your best chance, find an area, like the top of a hill, where you can have unobstructed sky views to the north.
If the conditions are good and you’ve found a solid lookout spot, remember to have patience. Much like it’s impossible to predict the exact moment it’ll start snowing, there’s no way of saying with certainty exactly when the aurora borealis will appear (or how long it will last).
This article originally published in 2022 but has most recently been updated on September 18, 2023 with new information.