Aurora Borealis Season Begins With Spring
If you’re lucky enough to live in the northern hemisphere and even luckier to live near the arctic circle, this is prime time for viewing the Aurora Borealis. For some unknown reason, the Aurora Borealis seems to be more active during the spring equinox. Of course, if you lived in the southern hemisphere near the South Pole, you’d be looking forward to viewing the Aurora Australis – but that’s a completely different story!
Auroras – which are also referred to as the Northern or Southern Lights – generally occur in the ionosphere and are seen as swirls or curtains of colored lights in the night sky. This phenomenon is usually confined to the polar regions and is caused by the solar wind – the stream of ions that continuously flows outward from our sun. When these ions collide with Earth’s atmosphere, molecules and atoms release energy in the form of photons and can be seen by us earthlings.
The increases and decreases in auroral displays are generally linked to changes in solar activity. When solar activity is high, as evidenced by a greater number of sun spots, Earth’s atmosphere is bombarded with a larger amount of particles in the solar wind. This causes auroral displays to be brighter and more wide spread. If you could see the Aurora Borealis from space, it would look like a thin ring of light circling the polar regions.
I know what you’re thinking….if auroras are caused by the solar wind, what would the spring equinox have to do with it? Great question! One explanation is that the Earth is actually “connected” to the sun by magnetic ropes. The solar wind travels along these ropes to interact with our atmosphere. It seems that these magnetic ropes are more organized or better connected during the spring equinox.
For more information, check out NASA’s THEMIS (Time History of Events and Macroscale Interactions during Substorms) project which is designed to learn more about this beautiful phenomenon.