Specific Physics of Nature/Wildlife Photography -- Aurora Borealis

- The Aurora Borealis is one of my personal favorite natural subjects to photograph.
    - Essentially, the aurora is just molecules in the atmosphere becoming "excited" or charged and then returning to their normal state which emits a light depending on the molecule and charge.
    -  The sun is what starts the aurora process.
       - The sun is constantly giving off energy through different reactions like nuclear fusion. This output of energy makes it way towards earth at an astonishingly fast rate, hitting earth's magnetic field in as little as 18 hours sometimes. We call these solar winds or solar storms.
    - When these solar winds/storms make contact with the earth's magnetic field most are directed around the earth, but some gets pushed towards the two poles of the earth. They are directed this way because of how the magnetic field is shaped. The magnetic field is meant to help block harmful rays from entering the earth's atmosphere. This is why most of the solar winds are blocked and redirected away from earth and only a small portion gets pushed towards the poles.

- The solar winds that do get directed towards the poles are what excites these different molecules to produce the aurora.
- Different molecules excited at different altitudes will produce different colors when ionized and excited. For example: oxygen, when ionized at an altitude above 180 miles will produce a red color; when oxygen is charged below 180 miles, it will produce a green - yellow color.
- Hydrogen and Helium will produce a blue and purple color but these colors are very rare and hard to see with the naked eye.

Viewing the Aurora
- Like I explained before, the earths magnetic field directs the solar winds to the earth's poles. This makes the aurora only visible around the earth's poles and a little distance below. You will not see the aurora in a country such as Ecuador which is along the equator.
- The optimal viewing of the aurora is along what we call the "aurora oval" (pictured in the above image by the green circles at each pole). This is the area along the earth's poles where the solar winds get direct to, which make it prime aurora viewing zones. Fairbanks is basically directly underneath the aurora oval making for one of the best aurora viewing areas around where the aurora tends to be seen directly overhead.
- Places that are not in the aurora oval can still see the aurora depending on how far they are below it and how strong the aurora is, the aurora will just appear lower on the horizon.

- Photographing the aurora is much different than just viewing it. Typically, the camera sensor is more sensitive to light than our naked eyes are, making it easier for the camera to pick up the aurora when we cannot see it.
- This sensitivity to light, also makes the camera better to capturing colors that our eyes may not be able to view. Sometimes the aurora can appear as just a dull green or brown to our eyes, but the camera may pick up blues, reds, purples, etc...
- The best way to photograph the aurora is through a long exposure. This is when you have the shutter open for a 'long' period of time such as 1 - 30+ seconds. This allows the camera to absorb all of the light possible to make a correct exposure of the aurora.