Last night was one of those nights that will be very hard to forget for the lucky bunch that went on deck to find an amazing Aurora Australis dancing on the night sky. What an amazing experience!
I remember thinking, exactly six months ago when the opportunity for this expedition came along, 'I will get to see Auroras down there'. I had not lost my hopes here on the ship, but the doubtfulness was circling me. I had not seen a single one in the almost four weeks that I have been in the Southern Hemisphere. Skies have been mostly overcast, and we did not even had a sunset while at McMurdo. Last night was different; we had the most amazingly clear night I have seen in decades. Even without Auroras, that starry sky would have been memorable.
An Aurora Australis. The dots are stars on the background.I like the pictures that I am posting here, but they do not show the whole amazing Aurora. I was only able to capture the brightest part of the Aurora, about 20-30% of it at most. Had we been on land, I would have set the camera for longer exposures, but that is not a good idea when the boat is constantly moving. I tried longer exposures in which stars and auroras were smeared by the ship's restlessness.
The chief mate called the lab to let us know there was a faint Aurora visible. We all rushed to the upper deck where we found a faint greenish band crossing the Sky from West to East, the same direction in which we were traveling. There were a few cumulus clouds just above the horizon, but it was completely clear elsewhere.
And then, a brighter narrow band appeared on the West side where the Orion constellation was. The show was just beginning. The very bright lights danced towards the East along the North side as a wider band.
An Aurora over part of Orion's constellation. Orion's belt is visible to the right of the green light. The star Betelgeuse appears red on the lower right corner and the star Rigel is the brightest white spotAn Aurora is light emitted at the upper layers of the atmosphere. The light is created when fast moving particles arriving from crash with air particles. These particles are what we call solar wind. You might ask, If that were the case, why are Auroras more visible near the poles? Because the Earth has a magnetic field around it that funnels the solar wind particles towards both Poles. How does this work? How can the magnetic field of the Earth change the direction of very fast moving particles? Tricky; because many solar wind particles have an electric charge, and any electric charge that is in motion generates a magnetic field.
What this means is that the charged solar wind particles are little magnets in front of the very large magnet that is the Earth. If you have played with magnets, you know that the small magnet will move towards the big magnet and that both magnets bind by their poles. Just like that, the small particles move towards the big one's poles.
Auroras are also visible at midd latitudes when there is a lot of solar wind; like when there are lots of solar flares. I remember seeing an Aurora Borealis in Madison, WI on a clear November night six years ago.
In case you did not know where the name comes from: Aurora is the name for the goddess of dawn in Roman Mythology. After seeing an Aurora, I completely agree on using that name. The difference between an Aurora Borealis and Aurora Australis is where they occur; Borealis means North and Australis means South.
I was happy to have stopped for my antarctic red parka on the way to the deck. Others had to go back inside after a quick look. I stayed for a long time and saw other filaments begin their journey through the sky back on the stern, where Orion hovered. They travelled towards the bow changing their shape and brightness. We were all busy looking towards the North at one of these traveling bands, when I turned to the South to find an even brighter area of green light. It was amazing, they were everywhere! At one point the lights were above us, just over the Southern Cross constellation.
Aurora over the Southern CrossI am not familiar with the Southern Hemisphere nigh sky, so I came prepared with an amazing free planetarium software to learn about the stars down here (Stellarium). I took a screen shot of Stellarium, in which I had played with the settings to make it look like the picture I took of the Aurora (Relative Scale 1.85). I was able to identify all the stars on the picture and learn about the constellations used by the Western world (I will write an entry on the constellations later and talk more about Stellarium). Phenomenal, simply phenomenal!
A screen shot from the software Stellarium to show the constellations visible in the picture of the Aurora over the Southern Cross.That was quite a ride. Even as I was warming up in my bed a couple of hours later, I wondered if they would still be out there and if I should go out as well. It might take another four weeks more to see them again, or they might not be out at all during the rest of the trip!
And one more personal thought, it was a magical night that missed one important ingredient to be complete; I wish I had been able to share it with my family. That will be on another day.