🌌 Northern and southern lights

Why the sky glows green near the poles, and how a solar storm makes the ring grow.

Lights in the sky
On dark nights near the poles, the sky can glow green, in shapes that ripple and change. In the north, these are the northern lights. In the south, they’re the southern lights. So where do they come from?
A wind from the Sun
The Sun is always blowing out tiny bits of matter with an electric charge. This is the solar wind. It rushes through space at more than 1.6 million km an hour, and some of it heads straight for the Earth.
The Earth’s magnetic shield
The Earth acts like a giant magnet, and its magnetic field bends most of the solar wind round the planet. But a few bits sneak in. They spiral down the field towards the magnetic poles.
A ring of light
The bits from the Sun crash into the air high up, and make it glow. Because they come in near the magnetic poles, the glow makes a ring round each one. It’s mostly green, about 100 km up. (The rings are drawn simply.)
Solar storm!
Sometimes the Sun throws a giant cloud of particles at the Earth. Then you get a geomagnetic storm, and the ring grows towards the equator. Slide to make a stronger storm. (This is a simple drawing, not a live forecast.)
Quiz time
The lights make a ring, but what’s in the middle of it? It isn’t the North Pole.

⭐ Remember

The Sun blows out tiny charged particles: the solar wind.
The Earth’s magnetic field steers some of them near the poles, where they make the air glow in a ring.
In a big solar storm, the ring grows towards the equator, so more people can see the lights.

The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).