Churchill once again is welcoming travelers from around the globe to witness the scintillating display of aurora borealis activity. The Churchill region provides optimal conditions, especially this time of year, for consistent, prolonged viewing of this amazing spectacle. Barring the dynamic cold temperatures, one can see the “Northern lights” with little interference in the sky in this special location on the Hudson Bay. Over the next three weeks I will post updates on the conditions and experiences of travelers in Churchill.
For the Northern lights to occur, three distinct phenomena must come together. Luckily, in the skies over western Hudson Bay, this happens about two hundred and fifty days out of the year.
Firstly, ninety three million miles away sits our sun – the source of most all energy here on earth. While sunlight travels that distance in around eight minutes, we now know other forms of energy are also emitted from our sun. Some of this energy is released in the form of charged particles like electrons and protons and are referred to as the solar wind or space weather. There seems to always be some space weather at any given time of the day or night. Through flares and magnetic disturbances on the surface of the sun, these particles are shot into space. Depending on the magnitude of these events, the particles or solar wind are propelled through space at varying speeds. It may take three to five days for the particles to reach the earth’s orbit. If the earth is in the path of of the solar wind then our second phenomena comes into play.
Earth’s Magnetic field
Secondly, the molten core of our planet is comprised of a dense iron mass that works to generate a magnetic field which radiates over two hundred and fifty thousand miles out into space. This magnetic field works as a shield buffering the earth from the solar wind and altering the course of the charged particles, redirecting them around the earth. Some of the solar wind gets redirected into the magnetic field itself and then pulled down into the polar regions of the earth known as the auroral zone or auroral oval. This is where Churchill enters the scene – during most nights of the year, the auroral oval sits directly overhead. The magnetic field folds and bends, accelerating the charged particles down into the earth’s atmosphere – our third component. On nights with a particularly strong solar wind, the interaction of the charged particle bends the auroral oval and the aurora can be seen much further south.
The earth is surrounded by a rich envelope of gases, primarily nitrogen and oxygen. When these particles are streamed down into the upper atmosphere, they inevitably collide with these molecules/atoms and release energy in the form of heat and light. The light we see is the aurora borealis (northern hemisphere) and aurora australis (southern hemisphere). We do not feel the heat because it is too far up in our sky. The different gases produce different colors of light. Most clear nights the green glow of the northern lights can be observed and photographed over Churchill. On some nights with enough solar wind viewers may be treated to the glows of reds and purples.
Photo gear: A good sturdy tripod is a must and I recommend a head lamp with a red filter for freeing the hands to work with the camera while not disturbing the travelers night vision.
A rundown of how to photograph the Northern lights can be found in an article at Patrick Endres’ web site alaskaphotographics.com.