Explainer: Why aurorae lights differ in colours around locations

Aurorae were seen from around the motu and the world yesterday as Earth continues to ride out the largest solar storm in decades.

The National Space Weather Prediction Centre issued the first severe geomagnetic storm watch in 20 years following a series of solar flares and coronal mass ejections that began on Wednesday.

Many star-gazers have shared their dazzling snaps on social media, which varied in colour depending on location.

Most aurora photos from around Aotearoa showcased a vivid magenta, a stark contrast from the green hues seen in the Northern Hemisphere.

In the north, the light display is known as the aurora borealis and in the south it's called the aurora australis.

According to NASA, the colour of the aurora depends on which gases are being agitated by electrons and how much energy iwas being exchanged.

"Oxygen emits either a greenish-yellow light (the most familiar colour of the aurora) or a red light; nitrogen generally gives off a blue light.

"The oxygen and nitrogen molecules also emit ultraviolet light, which can only be detected by special cameras on satellites."

Royal Museums Greenwich said the main gases in Earth’s atmosphere were nitrogen and oxygen, and these elements gave off different colours during an aurora display.

"The green we see in the aurora is characteristic of oxygen, while hints of purple, blue or pink are caused by nitrogen.

“We sometimes see a wonderful scarlet red colour, and this is caused by very high altitude oxygen interacting with solar particles. This only occurs when the aurora is particularly energetic," Royal Observatory astronomer Tom Kerss said.

Experts said last night was the best time to catch a glimpse of aurorae and it was unclear whether they would be visible again tonight.

Astronomer Rob Davison told 1News the best chance of seeing the display was getting as far south and as far away from light pollution as possible.