If you have, I bet you still remember your first Aurora encounter vividly. My first sighting was purely accidental. I was out photographing the night sky, and noticed a strange glow on the horizon, where I knew there shouldn’t normally be a glow. I had no idea what it was, but once I looked at the image my camera captured, it was pretty obvious to me that there was an Aurora Australis happening.
– This is a guest post by Francois Fourie. Thanks Francois!
In the Sun’s atmosphere, magnetic fields turn the outer layers into sunspots. Plasma gets blasted into space, and their force-lines stretch and break.
These solar flares propel particles into space, and if Earth directed, interact with the Earths magnetic field a couple of days later.
Charged particles emitted from the sun during a solar flare penetrate the earth’s magnetic shield and collide with atoms and molecules in our atmosphere. These collisions result in countless little bursts of light, called photons, which make up the aurora.
Solar flare activity rises at the height of the Sun’s 11 year cycle. The current cycle peaked around 2014, and activity is now slowly declining. There is however still great potential to see it, especially in winter, when we have more hours of darkness.
It’s near impossible to say exactly when the next one will be in advance. It really does depend on a lot of factors. Your best bet to see it is to just get out under a clear sky and have look. It also helps to be prepared, so that when you learn one is happening, you can be ready with short notice.
Head South, as far as you can. If you reach Tasmania, you are far enough.
Find a spot where you have a clear view of the horizon when looking South.
Ideally pick a spot away from any light pollution where possible.
A good idea is to scout for locations during daylight hours, so that you can see where you are going, and get familiar with your surroundings. Go find that perfect foreground element if you wish to take a great photograph. Remember, it needs to be South facing.
A full moon is quite bright, and can also have an impact on how much of the Aurora is visible, so keep that in mind.
The colours are specific due to particle energy and atmospheric pressure.
Green is due to excited oxygen atoms at heights of 100-200km.
Red is usually visible above 200km.
Below 100km, nitrogen molecules are stimulated to glow with red, blue, and violet light.
Glow is produced in vertical sheets, appearing as curtains waving slowly
Ideally you should have a DSLR camera with manual controls, so that you can adjust the ISO, Shutter speed and Aperture.
Choose a wide-angle lens, so that you can fit in as much of the scene as possible. A fast lens (low f/stop) will also be beneficial to allow as much light as possible to hit the sensor.
Choose the highest ISO your camera can handle while still producing images with acceptable noise. Start around ISO 800, and work your way up. My Nikon D800 works well around ISO 2500-3200
Depending on your lens, f/2.8 to f/4 would be ideal. Choose the lowest f-stop value on your lens, and examine the results
Auroras move, so the shorter you can keep the exposure time, while still allowing as much light as possible to enter, the more detail you will see in the “curtains”. Try between 8-20 seconds.
Your camera and lens needs to be switched to manual focus. (Auto focus is useless at night) Now adjust the focus ring to infinity, or focus on a bright subject far away in the distance. Take a picture and check your photo, now adjust and repeat until you get sharp focus.
Visit websites such as spaceweather.com, or aurora-services.net. Facebook is also a great source of information, where you can connect with thousands of like minded Aurora chasers, just search for Aurora Australis.
Don’t worry, I’ve got you covered, just watch this video.
About the Author, Francois Fourie:
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