Aurora Map

What an aurora map actually shows

Aurora doesn't form an even glow across the whole polar sky — it concentrates in a lopsided ring called the auroral oval, centred on the geomagnetic pole rather than the geographic one. On a map that ring is usually drawn as a band of colour draped over the top of the globe, brightest on the night side and thinner toward the day side. Most public aurora maps render the OVATION model, a NOAA product that estimates the probability and intensity of aurora across the oval by feeding the latest solar-wind measurements into a statistical model. What you're seeing is a short-term nowcast, typically projected 30–60 minutes ahead — not a live photograph of the sky.

The colour on the oval represents energy flux, not brightness through your eyes. A patch shaded strong red or white means more energetic particles are raining into the upper atmosphere there, which usually corresponds to a better chance of a visible, active display beneath it. Because the model leans on solar-wind data measured upstream at the L1 point, roughly a million miles sunward of Earth, the map updates as fresh readings arrive and shifts within minutes when conditions change.

How the oval expands during a storm

On a quiet night the oval hugs high latitudes — a thin ring over the Arctic that only far-northern observers in places like Iceland, northern Norway or Alaska sit beneath. When a geomagnetic storm arrives, that ring grows: the whole oval widens and its equatorward edge pushes toward lower latitudes. This is why a storm can put the aurora over regions that never normally see it. The trigger is almost always a stretch of strongly southward Bz — the north–south tilt of the interplanetary magnetic field turning negative — which lets solar-wind energy couple into the magnetosphere. Pair that with faster solar wind (roughly 300 km/s on calm days, climbing well past 500–800 km/s in a storm) and the oval bulges outward.

Storm strength is graded on the G1 to G5 scale, and it tracks closely with how low the oval reaches. A modest G1 nudges the ring a little south of its quiet position; a severe G4 or extreme G5 can drag the equatorward edge down over mid-latitudes. The KP index (0–9) is the number most maps use to place that edge: higher KP means a larger, lower-reaching oval. Watching the oval grow on a map alongside a rising KP and a diving Bz is the clearest early sign that a display is building — see the aurora forecast for how those inputs combine.

The viewline: how far south you can see it

The most useful line on many aurora maps isn't the oval itself but the viewline — a curve drawn well equatorward of the oval marking how far south the aurora may be visible on the horizon, even when it isn't directly overhead. This matters because aurora happens high up, typically 100 km or more above the ground, so it can be seen from hundreds of kilometres away, glowing low to the north like a distant sunrise. If you live south of the oval but north of the viewline during a storm, look toward the pole rather than straight up.

A few practical caveats the map can't show you: the viewline assumes a clear, dark sky with an unobstructed horizon and no light pollution. A bright Moon, city glow, low cloud or hills to the north will all cut down what actually reaches your eyes. The oval also pulses — it can brighten and surge (a substorm) and then fade over tens of minutes — so a map showing quiet conditions doesn't rule out a burst an hour later. Treat the viewline as "worth watching from here," not a guarantee. Cross-check with tonight's outlook before you commit to a drive.

Two ovals: north and south

There isn't one aurora — there are two, and they're near-mirror images. The northern oval produces the aurora borealis; a matching oval circles the south magnetic pole and produces the aurora australis, the southern lights seen from Tasmania, southern New Zealand, southern Chile and Antarctica. The two ovals are roughly conjugate, driven by the same solar wind hitting the same magnetosphere, so when the north lights up the south generally does too. That's why global aurora maps often show both polar caps: the physics — southward Bz, solar-wind speed, KP and storm level — applies identically at each end of the planet, just flipped so that "equatorward" means north in the southern hemisphere. If you're curious how the whole chain from Sun to sky fits together, the space weather overview walks through it.

Aurora map FAQ