The aurora is the only thing in the sky that moves while you watch it. Charged particles from the sun follow Earth's magnetic field down into the upper atmosphere and make it glow — green from oxygen at 100–150 km, red higher up, violet and pink from nitrogen along the lower edge. It cannot be booked. You put yourself under the auroral oval during the dark months and the sky decides.
That oval is a ring, not a place, and it has a southern twin. The same storm that lights up Tromsø lights up Tasmania and Stewart Island on the same night — the difference is that far fewer people live under the southern ring, so it has fewer roads, fewer guides and darker skies. The seasons invert: September to April in the north, March to September in the south.
Three things decide whether you see it: darkness, clear sky and geomagnetic activity. The first two are geography and luck, the third is the sun. Solar maximum passed in October 2024 and the cycle is declining, but the declining phase historically throws some of the biggest individual storms, and NOAA expects activity to stay high into 2027. Plan three or four nights, not one — cloud is the enemy far more often than a quiet sun.