Spark and Perl go looking
The sky is on fire.
Green fire, and it is moving.
Look down, not out. We are above the top of the world.
That is happening in the air below us, not out here in the dark.
Who lit it?
The Sun. It throws little pieces of itself out all the time, and now and then a great cloud of them.
The Earth catches them with its magnetism and pours them down in a ring round each of the two poles.
Why green?
Oxygen, high up, hit hard enough to glow. Higher still it glows red, and nitrogen makes the purple along the bottom edge.
So these lights are an Earth thing. We are the only ones with them.
Almost every world with magnetism has them.
Mars, then? Mars has hardly any magnetism left.
Which is why Mars does not get a ring round its poles. It gets the WHOLE SKY glowing green at once.
A robot standing on the ground photographed one in 2024.
And Jupiter?
Jupiter’s never stop. It spins fast enough to keep them lit by itself — and Io’s volcanoes throw up the stuff that feeds them.
Far north or far south, often. From where most people live, a few times in every eleven years — that is how long the Sun takes to go from calm to stormy and back. Even then it is a faint glow low down near the horizon, not the curtains in the photographs.
Watch for news of a storm leaving the Sun, then go out and look: north from the northern half of the world, south from the southern half.
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