Icelandic Rivers of Light, by Sergio Díaz Ruiz, Spain

Second place in the 2021 IAU OAE Astrophotography Contest, category Aurorae (time-lapses)

This video shows how aurorae evolve slowly over timescales of a few minutes. Note the clouds being illuminated from behind in the last two shots. Aurorae are caused by interactions between the charged particles blown out in huge explosions from the Sun and the Earth's magnetic field. The changes over time are caused by huge waves of particles pushing the Earth's magnetic field into strange shapes before it snaps back into place.

Credit: Sergio Díaz Ruiz/IAU OAE