aurora borealis

What is the aurora borealis?

Explaining the effects of the Spring Equinox and Solar Energy

RMetS
09 May 2018

The Vernal, or Spring Equinox falls on the 20th or 21st of March depending on the year. In 2013 it is on the 20th March.

Around this time of year there is an increase in the number of occurences of Aurora Borealis, or the Northern Lights. These are manifestions of extreme conditions and are caused by solar energy. Solar energy enters the earth’s magnetic atmosphere and causes disruption of the earth’s magnetic field, see the image on the right (Courtesy NASA).

The Aurora Borealis, seen below, can appear as green curtains of light across the sky. They are more frequent in Spring. But how does the sun know that Spring has arrived on earth? NASA has launched THEMIS, a mission with a team of five space craft, to study auroras. One geomagnetic storm that NASA observed had a total energy of five hundred thousand billion (5 x 10^14) Joules. UCLA physicist Vassilis Angelopoulos pointed out that is nearly the same as an earthquake of 5.5 magnitude!

There is a lot still to be understood about Aurora (Borealis in the Northern Hemisphere and Australis in the Southern). Angelopoulos says that “Auroras sometimes erupt with little warning and surprising intensity. We call these events ‘sub-storms,’ and they are a big mystery.”