Here are some tips for your excellent aurora photos. Try to keep them under your pillows!
SCIENCE OF THE AURORA BOREALIS
What Causes the Aurora?
Scientists explain the Aurora Borealis as an atmospheric response to solar winds – high energy clouds of ion particles emitted by the sun. As the winds reach the Earth’s magnetic field, some of the ion particles are trapped by it. They’re drawn down into the ionosphere, where they collide with gases above the Earth’s surface to produce the glowing colours of the Aurora Borealis. Most Auroras occur about 100 to 1,000 km (60 to 620miles) above the Earth.
What Makes the Northern Lights Dance?
Since 2009 is the International Year of Astronomy, we should note that scientists have made remarkable progress in the study of Auroras. In 2008, for instance, researchers using a fleet of five NASA satellites discovered that explosions of magnetic energy a third of the way to the moon, power substorms that cause the sudden brightening and rapid movements of the Aurora. These magnetic disturbances cause the lights to pulse across the sky and theurora Coloursn subside, leaving small patches of Aurora that blink on and off for up to an hour or more. There can be several substorms per night. In fact, an estimated 1,500 substorms occur every year, sometimes several days apart.
Can You Hear the Aurora?
Northern people might tell you they’ve heard the Aurora, describing swishing and cracking sounds synchronized with the movements of the Lights. Researchers have examined the possibility that sounds could be transmitted directly or via electromagnetic waves transduced into acoustic ones. The biggest argument against these ideas is the fact that Auroral events take place very high above the Earth’s surface, and any noises they made could not be in sync with visible changes, simply because sound would take extra time to travel so far. No such sounds have ever been recorded.
The Earth’s atmosphere consists mainly of nitrogen and oxygen which, when ignited, emit characteristic colours. The most common Aurora colour is a ghostly green, given off by oxygen atoms. Oxygen is also responsible for the brownish red at the very limit of human vision. Very intense Auroras have a purple edge at the base, a misture of blue and red emissions from nitrogen.
Naming the Aurora?
Galileo (1564-1642), the founder of modern astronomy, thought the rarely-seen lights were caused by rays from the rising sun as they bounced off the Earth’s atmosphere. When he needed a Latin name for the phenomenon, he chose that of Aurora, Roman goddess of the dawn. 2009 is the 400th anniversary of the year Galileo first turned a telescope to the skies.
THE FIVE AURORA TYPES
TYPE A is a green Aurora with red hues on top. This is caused by a combination of energized particles. The strong ones penetrate deeper down into the atmosphere and bring dense oxygen atoms to their second excited phase, where they emit green photons. The weak particles reach only the upper atmosphere and bring the less dense oxygen atoms to their first excited phase, where they emit red photons.
TYPE B and E are green Auroras with red hues on the bottom. This occurs when strong energized particles reach altitudes as low as 70km. The oxygen at the 100-150km level will emit the expected green photons. Because oxygen is less dense in the lower regions, it will only reach its first excited phase and emit red photons. Nitrogen molecules are more dense in this region and will also emit strong red colours.
TYPE C is a green Aurora caused by a particle beam that reaches the 100-150km level of the atmosphere. Here, oxygen is more dense and the powerful solar particles will push te oxygen molecules to their second excited stage, where they immediately emit a green photon.
TYPE D is a red Aurora that occurs when there is a weaker energy emission from the solar winds, reaching only the upper atmosphere. Here, oxygen is less dense and emits a red photon in its first excited stage.
TYPE F is a blue/purple sunlit Aurora. It occurs when sunlight falls on the high atmosphere in early morning. Particles from the solar wind ionize nitrogen molecules, which emit violet and blue colours. These colours are usually difficult to see, but they absorb the light from the sun and re-emit its energy, causing brighter light.
YOUR AURORA VIEWING WARDROBE
What you’ll need to wear to stay warm
The Aurora is usually at its best on cold, clear nights, and the right clothing is an essential part of your winter Aurora-viewing experience. To ensure your comfort, many NWT tour operators can provide state-of-the-art Northern outerwear. Here’s a wardrobe checklist to keep you cozy from head to toe, even if the temperature dips to -40 degrees.
A wool toque you can pull down over your ears and forehead. Suitable for average winter days and an easy fit under a parka hood for colder days or nights. You might also want to add a wool scarf.
A down-filled parka with a fur trimmed hood to protect your face. The best parkas are good for -50 degrees. Yours should be big enough to fit comfortably over a wool sweater or fleece jacket.
- Heavy duty lined mitts with cuffs that fit under the sleeves of your parka (or gauntlets that fit over them), to eliminate cold drafts around your wrists.
- Lined wind-kpants to wear over your regular jeans or trousers. The warmest have a front bib and shoulder straps, to retain body heat in your torso.
- Knee-high boots with big rubber feet, nylon tops, and thick felt liners with lots of room for wool socks. Although it takes a little while to get used to these functional fashion statements, they’re tops when it comes to keeping your feet warm during extended periods outdoors.
LIGHTS. CAMERA. ACTION.
When it comes to the Aurora, most of us hope to take the kind of picture that speaks a thousand words. But it’s not as easy as just pointing and clicking. Here are a few tips to help score your perfect Aurora shot.
- CAMERA: A single-lens reflex camera(SLR) is ideal because it allows you to control camera settings and the final exposure. Film and digital shooting are virtually the same, but even the best digital camera produce some “digital noise.”
- THE LENSES: Use a lens with an aperture of f3.5g or better (the lower the number, the faster the lens). A speedy lens will maximize contrast by allowing in more light on dark nights. Get all of the Aurora with a wide-angle lens (24-35mm) or an ultra-wide angle (10.5-21mm).
- FILM SPEED AND ISO EQUIVALENT: For best results, use a film (or ISO equivalent in digital cameras) of 200 or 400. Set a longer exposure at ISO 200. From there, you can experiment with different speeds to discover that perfect shot.
- SNAPPING THE SHOT: You’ll need a sturdy tripod and a good shutter release cable that can stand up to the cold. Pick your location. An interesting and a typical foreground will really add interest and scale to your photograph.