The Southern Lights, Tasmania. Video: Gary Plummer

 

 

Some holiday makers in Tasmania were last night treated to a ‘Southern Lights’ display in the southern sky!

 

There was a display of subtle green glows with a few pulsating beams, seen in Huon Valley nearby the forested Mount Misery Habitat Reserve; a few hundred metres to the Labyrinth, which is a maze of tarns, lakes and fantastically named mountains in the heart of Tasmania's wilderness.

 

Here, some holiday house guests were given a clear view of the southern sky where the Aurora was active.

 

The Southern Lights, also known as Aurora Australis, is sometimes seen in the southern sky from many areas of Tasmania. The best places to see them are those with open sky to the south and no city lights. Buttongrass Retreat, Port Huon Cottages and Clifftop Cabin at Huon Bush Retreats are all suitable holiday houses to base yourself on an aurora active night.

 

The Southern Lights is the southern hemisphere counterpart to the Northern Lights, also known as Aurora Borealis. In the sky, an Aurora Australis takes the shape of a curtain of light, or a sheet, or a diffused glow and is most often green, sometimes red, and occasionally other colors too.

 

Southern Lights

The Southern Lights. Photo credit: Helena Wisby

 

Like its northern sibling, the Aurora Australis is strongest in an oval centered on the south magnetic pole. This is because the lights are the result of collisions between energetic electrons (sometimes also protons) and atoms and molecules in the upper atmosphere. The electrons get their high energies by being accelerated by solar wind magnetic fields and the Earth’s magnetic field. The motions are complicated, but a basic explanation is that electrons spiral around the Earth’s magnetic field lines and ‘touch down’ near to where those lines become vertical.

 

Consequently, the best place to see aurorae in the southern hemisphere is Antarctica at night! Since only a very few venture to Antarctica, your next best bet is Tasmania! When the solar cycle is near its maximum, Aurora Australis is also sometimes visible in New Zealand - especially the South Island and southern Chile and Argentina.

 

In regard to the stunning colours, the physics are similar to what make a flame orange-yellow when salt is added to it like specific atomic transitions in sodium atoms. The green and red come from atomic oxygen and the pinkish-reds and violets come from nitrogen ions and molecules.

 

Photo credit: Matt Glastonbury

 

The Southern Lights are typically 100 to 300 km high. This is where green is usually seen, with red at the top. It is sometimes even as high as 500 km and low as 80 km. When you see the colour purple, the aurora is likely to be this low.

 

It isn’t just Earth getting all the action! Did you know that spectacular auroras are also seen on other planets including Jupiter and Saturn where there are strong magnetic fields together with moderate solar wind and deep atmosphere?

 

Unless you spend your life chasing these auroras, seeing one really is special and unique opportunity; possibly a once-in-a-lifetime experience. Can you imagine how remarkable it would be?!