Aurora Q&A

The information gathered prior to my trip to Sweden is compiled as a Q&A session here.

[Home] [Study] [Aurora Link] (Created 2001-04-19)

How Aurora is generated? The Sun is constantly emitting electrons and other particles. This flow of particles is called the Solar wind. Electrons that came near Earth are captured by the Earth's magnetic flux and carried to both North and South magnetic poles. There, electrons collide with oxygen and nitrogen atoms in the earth's atmosphere. This causes oxygen and nitrogen atoms to emit light. The neon tube generates light with the same mechanism.
This results in whitish belt of light in the sky when the Earth's magnetic (geomagnetic) field is stable. Rapidly moving curtain of light appears when geomagnetic field is agitated somehow. This is the Aurora.

What is the 11-year period of Sun's spots? Number of Sunspots increases and decreases with the period of 11 years. When the number of Sunspots is large, the Solar wind becomes stronger and geomagnetic field is disturbed more, resulting "magnetic storm". When this happens, short-wave radio transmission is sometimes disrupted. However, chances of viewing Aurora of grand scale increases.
Middle of year 2000 was the most recent peak of the solar spots. Therefore, now is the best timing for viewing the Aurora.

When is the best time? Winter, when the night is long, is the best season. Also, choose Moon-less nights.
Other obstacles are clouds and snow. You will have to rely on your luck on those conditions because you cannot control them.

How do you know the Moon phase? There are several resources on the Internet. This web site has a page which shows any specified month's Moon phase in calendar format.
This web site has a page which shows dates of new moon for the specified year. This is very helpful for planning purposes. (in Japanese)
For those of you who prefer doing the calulations by yourself, Caluculation Formura can be found here. (in Japanese)

How about taking photos? Here are some tips for taking photos.

Battery operated cameras cease to operate under -30 to -40 degrees (Celsius) temperature. Therefore, either use a fully mechanical camera or a battery operated camera with some warming arrangement. Also avoid rapid film winding to prevent breaking the film or generating static which will expose the film.

Wide-angle lens of 28mm or less focal length with at least 2.8 aperture is recommended because Aurora tends to appear in a large area of the sky.

As for film sensitivity, ASA 400 will be good. Higher sensitivity films such as ASA 1600 enable shorter exposure times but tend to produce granular images. Negative films are recommended because reversal films have narrower ratitude. Take the same scene with several exposure times, between 10 second and 1 minute.

Put the camera in a plastic bag and close the mouth tightly before bringing it into warm room. Otherwise, the moisture in the room will condense on the camera lens.

What to do when we are at site? Geomagnetic activity has its own mind. Therefore, you will have to just wait until Aurora appears. Meanwhile check web sites #5 and #14 as often as possible.
Duration of active Aurora can be as short as 15 minutes. Go outside and check the sky as often as possible. Taking turns with your friends is a good idea.

What about clothing? In my experience, one more layer of clothing over "Skiing outfit" was sufficient for temperature at -36 degrees Celsius. More specifically, I wore long john + jogging trousers + skiing trousers for lower body and thick under shirt + two layers of sweater + feather stuffed jump suit for upper body. Also you need something to protect your face and a hat.

I want to learn more about the Aurora. There are a lot of Aurora sites in the Internet. #1 in my link list contains learning materials. #4 contains a BBS which is full of useful information.(in Japanese)

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