Earth’s auroras, popularly known as the Northern and Southern Lights, are indisputably beautiful. They are also, perhaps surprisingly, not mirror images .

You can imagine the two like mismatched dancers: Viewed from space, the Northern Lights may contort and groove in one direction, while the Southern Lights could perform a routine that doesn’t quite sync up with its partner’s.

Research published in December in the Journal of Geophysical Research: Space Physics, reveals that the cause of this north-south auroral asymmetry is the angle at which the sun’s solar wind and magnetic field approaches Earth.

[Sign up to get reminders for space and astronomy events on your calendar.]

Earth has two magnetic poles, a north and a south, much in the same way a bar magnet does. From these two poles, bunched up magnetic field lines — invisible tendrils that represent the direction and strength of this planetary bar magnet — reach out into space as the planet travels on its orbit. Like fishing lines, they catch energetically excitable particles heading our way in the solar wind. These particles slam into our atmosphere, and energy is released in the form of the colorful auroras.