The Aurora Australis graced Tasmania with another visit last Monday night. I arrived early to find dark clouds covering most of the southern sky, with tantalizing glimpses of the show coming through small breaks in the cloud. During this test shot, a plane took off from Hobart Airport and made its own mark on this particular exposure:
The situation seemed quite hopeless – it looked like there was a spectacular show going on behind the cloudbank, but that cloudbank showed no signs of moving. At one point it even started to rain and it seemed like all bets were off… until:
It was like Moses parting the Red Sea – all of a sudden the clouds were gone and the show was on! Unlike the Aurora in September, there was no moon at all in the sky Monday night, meaning the camera could capture all the colours of the aurora in all its glory. The pinky reds above the main green layer, which were not visible at all in the full moonlight of September 3, were stunning. The Magellanic Clouds too stood out this time and made a great companion to the main light show.
Photographing the Aurora requires a camera with good light sensitivity (ie High ISO capabilities) as apart from the tiny stars, the aurora is the only real light source in the image. Manual focusing to infinity is the only way to ensure a sharp image, as autofocusing will not work. Then of course a tripod is required to keep things nice and steady for exposures that will require anything up to 30 seconds (and beyond). The shot above was a 30 second exposure using ISO 3200. High ISO will result in a noisier image (and each camera model will have differing levels of “acceptable” noise), but it will capture light and colour that lower ISO’s will either not catch or will require a much longer shutter speed to capture. Long shutter speeds of course leads to star trails:
I took the above shot later in the evening as the aurora appeared to be retreating. This image is a 20 minute exposure, consisting of two 10 minute exposures. In fact I shot three 10 minute exposures, however, the incoming tide snuck up on me during the third exposure and caused the tripod to sink into the sand, ruining that one, so 20 minutes it is! For this image I reduced the ISO right back to 80, to compensate for the extreme long exposure. The reason for blending two images instead of taking just one 20 minute exposure was to reduce the risk of overexposing the aurora itself, which is basically the only source of light in the scene. The sun has been very active lately, and a couple of volatile sunspot regions (the source of the flares which can potentially cause the aurora) are now facing the earth. It could be that we will see some more action in the not too distant future. Check out Space Weather for info, and tune into my Facebook or Twitter feed for updates “as they happen”.
Good places to see the aurora in Tasmania:
Generally speaking, anywhere facing south with a clear horizon (ie low or no mountains or buildings) and away from the city lights will be great. Eg South Arm, 7 Mile Beach, Down the Channel (ie beyond Kingston) and along the Huon River south of Huonville. The top of Mt Wellington would offer a unique perspective but you would also be battling with the city lights.
NEW: Aurora Australis Tasmania page with links to all my aurora related posts, and other online references.