Get ready to potentially witness a spectacular celestial event tonight! A specific feature on the sun is expected to trigger a moderate geomagnetic storm, increasing the chances of seeing the vibrant Northern Lights (aurora borealis) much farther south than their usual polar range, potentially across around 15 U.S. states.
What’s Happening on the Sun?
The source of this potential light show is a “coronal hole” on the sun. These are vast, less dense regions in the sun’s outer atmosphere where magnetic field lines extend outward, allowing high-speed streams of charged particles – essentially, powerful solar wind – to escape into space at speeds of hundreds of kilometers per second.
When this fast-moving solar wind reaches Earth, it collides with our planet’s magnetic field, causing disturbances known as geomagnetic storms. The National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center forecasts a moderate (G2) geomagnetic storm for tonight, June 25th. While not the most extreme on the scale (which goes up to G5), a G2 storm is significant enough to push the aurora visibility southwards. Space weather forecasters measure this activity using scales like the G-scale and the Kp index, with a G2 storm corresponding to elevated activity levels. For context, much stronger solar events like severe (G4) or strong (G3) storms can cause auroras visible over an even wider area, reaching lower latitudes.
The current activity is primarily driven by this high-speed stream from the coronal hole, rather than a large solar flare or coronal mass ejection (CME), though the interaction between the solar wind and Earth’s magnetic field is crucial, particularly the orientation of magnetic fields carried within the solar wind.
Which US States Could See the Lights?
Auroras are typically most intense directly over polar regions like Alaska and Canada. However, the forecast moderate geomagnetic storm means the aurora oval is expected to expand south. Around 15 U.S. states, particularly those in the northern and upper Midwest regions, could potentially see the display on their northern horizon tonight. This includes states ranging from New York to Idaho, with likely viewing opportunities in states like Minnesota, North Dakota, Montana, Maine, Michigan, Wisconsin, Vermont, New Hampshire, Washington, Oregon, and South Dakota.
You don’t necessarily need to be directly underneath the aurora to witness it. The colorful light show can be seen from distances up to 620 miles (1,000 kilometers) away from where it is centered overhead, often appearing as a glow or dancing lights low on the northern horizon.
Why Do Auroras Appear?
Auroras are a stunning result of space weather interacting with Earth’s atmosphere. They form when the charged particles from the sun, accelerated by the geomagnetic storm, enter our planet’s upper atmosphere and collide with gas atoms and molecules, primarily oxygen and nitrogen.
These collisions excite the atmospheric particles, causing them to release energy in the form of light. The specific colors depend on the type of gas and the altitude of the collision:
Oxygen typically produces the most common green and red colors.
Nitrogen tends to create blue and purple hues.
The result is the breathtaking, often dancing, curtains and arcs of light we know as the Northern (or Southern) Lights.
Tips for Catching the Show
If you’re in one of the potentially visible states tonight, here’s how to maximize your chances:
- Find Darkness: Get away from city lights and light pollution as much as possible. Head to a rural area if you can.
- Look North: Find a location with a clear, unobstructed view looking towards the northern horizon.
- Timing: The best viewing opportunities are typically during the darkest hours, from just after sunset into the early morning before sunrise. In the northern hemisphere summer, shorter nights can make this window smaller.
- Check the Weather: Clear skies are essential. Clouds will block the view.
- Be Patient: Auroral displays can be unpredictable and vary in intensity.
While forecasts provide guidance, auroral activity can be notoriously tricky to predict with certainty.
Looking Ahead
Geomagnetic activity is expected to decrease after tonight. The forecast for Thursday, June 26th, indicates a return to minor (G1) storm levels.
Tonight presents a rare and exciting opportunity for millions across the northern U.S. to potentially witness the magic of the Northern Lights, fueled by activity on our dynamic sun. Good luck and clear skies!
