Sunday, March 30, 2008

Northern Lights

Over the past few nights we have been able to witness some spectacular Northern Lights. These atmospheric phenomena are also called the Aurora Borealis - a term coined by Galileo after Aurora, the goddess of morning. (If you were in the southern hemisphere, you'd call them the Aurora Australis). Ian managed to get some photos, shown here.

In this photo above, the blurry figure in the foreground is Ian. (The setting needed to capture the aurora leads to blurring of the foreground). This was just to prove that these are indeed the actual observed northern lights and not just something we googled for images. Behind Ian you can still see a bit of the twilight from sunset ... this view is looking north - the Arctic Ocean "beach" is in the background.

Our first indications of an active night would come around 11 pm - just when the last light of the evening twilight would diminish enough to give us a darkened sky. Whispy trails of greenish-colored "clouds" would appear and move and shimmer, moving generally from north to south. As they became more intense, they'd move quite rapidly and other colors of purples, pinks and blues would appear as well. This would generally keep up for a couple hours - and of course we stayed up for the whole show. At one point we decided to put down the tailgate of our truck and laid in the back to get a more comfy position for viewing.

It really is no wonder that there are mystical tales associated with the Northern Lights. There have been (and still are) many different beliefs about the aurora and their association with the spirit world. For example, the Algonquin believed the lights to be their ancestors dancing around a ceremonial fire. A less spiritual interpretation came from prospectors during the Klondike Gold Rush - the lights were supposedly the reflection of the mother lode of all gold. (For a great description of some of the aurora history - see the entry for aurora).

But what causes the aurora? The sun sends a constant stream of charged particles toward Earth. Some of these interact with the outer portions of our atmosphere ... the energy from this interaction gets transferred to oxygen and nitrogen present in the atmosphere (about 100 km above the surface of Earth). This excites the oxygen and nitrogen ... but the oxygen and nitrogen don't stay excited forever ... and to get rid of this excess energy, they emit characteristic wavelengths of light, which then are viewed from below as the aurora. (Again, wikipedia gives a good - albeit very detailed - description if you want the real hard-core details).

Whatever the cause, they are a spectacular sight.


Mom of Three said...

Just amazing. My nine year old says the bottom one looks like a dragon.

How much light are you getting a day now?

Dr G said...

I kinda thought that too about the picture. It was taken right above our head - it looked like it was "raining" light. really cool.

The sun is rising around 7 am now ... and it still is "twilight" outside at 10-11 pm. It doesn't get completely dark until after 11 pm. Soon, we'll be to 24 hours sunlight (around May 10 I think).