Nature's Show
—Allison Bedosky, Education Director
Last March, people in the United States were able to witness a colorful phenomenon known as the Aurora Borealis, or the Northern Lights. I can recall sitting in my own backyard around 9:30 pm and noticing streaks of green float by in the night sky. It wasn't the serpentine movement that can be seen from satellites, or the brilliant colors observed by those living in Alaska, but it was still impressive and worth asking, "What causes this?" and "Why don't we see this all the time?"
Well, it's actually a good thing that we don't see this frequently since these colorful, moving lights are the result of electrons from the Sun hitting the Earth's gases. The Earth's magnetic field acts as a shield by protecting us from the Sun's particles, which are constantly flowing. This flow of particles, called solar wind, hits our magnetic field as it blows away from the sun. This pressure causes the magnetic field to become cone-shaped. Although this cone-shaped shield continues to act as a barrier between Earth and the electrons, there are still some openings that allow the particles to enter.
These particles usually enter where the magnetic field, which acts like a bar magnet, has the weakest spots. The weakest areas tend to be at the North and South Poles, which explains why the Northern Lights are usually seen in parts of Canada, Alaska, and Russia. When the electrons flow into these weaker spots, they enter the ionosphere, which contains gas particles. When the Sun's electron particles make contact with the Earth's gases, the gas reacts by releasing this abundant energy. The energy comes off in the form of light, which is colored according to the type of gas that the particles interact with. For example, green and red light is caused by atomic oxygen, while blue light is the result of an interaction with atomic nitrogen.
Although I would love to see the Aurora Borealis more than once during my lifetime, I'm happy knowing that our magnetic field is doing its job keeping solar winds out. However, if it ever makes its way back to Connecticut or New York again, you can find me in my backyard, gazing up at the night sky.
