A light show powered by the Sun
The northern lights are light emitted by gases high in Earth's atmosphere. Their energy comes from interactions between the solar wind and Earth's magnetic environment. The solar wind is an ongoing flow of charged particles carrying a magnetic field outward from the Sun. It is present even when no large solar eruption is making headlines.
Earth's magnetic field deflects much of that flow, but the interaction can transfer energy into the magnetosphere. When that stored energy is released, energetic electrons can travel along magnetic field lines into the upper atmosphere. Collisions excite atmospheric atoms and molecules; as they release energy, they emit the light we see.
Why the lights gather near the poles
The magnetic field helps organize auroral activity into broad ovals around the magnetic poles. These are not fixed rings drawn around the geographic North and South Poles. Their position and shape change, so two places at the same geographic latitude can have different viewing opportunities.
This is why our map is more useful than a simple rule about going north. Start with the current oval, find a destination near it, and then check the actual sky. A location beneath an active region still needs darkness and a clear enough view to make the light visible from the ground.
Storms can make the oval expand
A coronal mass ejection is a large release of magnetized solar material. If one reaches Earth under favorable conditions, it can contribute to a geomagnetic storm. Fast solar-wind streams can also disturb the magnetic environment. These processes can bring brighter, more widespread auroral activity, but an eruption on the Sun is not a promise of a display at your location.
For planning, separate three questions: what is happening at the Sun, what has reached Earth's neighborhood, and what can be seen outside right now? Our short-term map addresses a different timescale from the three-day geomagnetic outlook. Read each timestamp before combining the two.
A fact to take outside
The aurora is not a layer of clouds reflecting colored light. It is the atmosphere producing light of its own. When you see a curtain, its folds are a changing view of a much larger three-dimensional structure overhead. Watch its shape for a few minutes rather than expecting a still image to tell the whole story.
Common questions
Do northern and southern lights have the same cause?
Yes. Aurora borealis and aurora australis are the northern and southern expressions of the same Sun–Earth interaction, although the two displays need not look identical.
Does every solar flare cause an aurora?
No. A flare announcement alone does not establish an Earth-directed disturbance or a local aurora forecast. Check subsequent space-weather measurements and the short-term model.
Sources & further reading
Start with these sources for the science and forecasting behind this guide.