Scientists predict upcoming decades-long lull
Many scientists are predicting a period of decreasing sun spots and practically no interactions between the sun's charged particles and the Earth's upper atmosphere, where aurora borealis, or the Northern Lights as they are commonly known, occur. That means, this may be one of the best winters for decades for people to see the Northern Lights, said Simon McMillan.
“We've observed over the past 10 years that solar activity is decreasing,” McMillan said. “So, even though we're at a maximum right now, it took a very long time before the last minimum ended, and this current maximum is quite weak.”
That being said, scientists understand the solar cycle very poorly, McMillan said, so the prediction that there will be a lull in solar activity for decades starting around the year 2020 “could totally not turn out to be the case. However, it has happened several times in recorded history, where there was a lull over several decades, so who knows.”
Aurora borealis in the northern hemisphere, or aurora australis in the southern hemisphere, is formed through an interaction between charged particles coming from the sun and the Earth's own magnetic field. The sun's charged particles lend their own energy to particles in the Earth's upper atmosphere, and they start to glow.
“Essentially, it's the sun's particles charging up our own atmosphere, and as the the energy is readmitted by the particles in atmosphere, it lets off the light known as aurora borealis,” McMillan said.
The colour of the aurora is dictated by several factors including the gas that is excited by the sun's particles (different gases will give off different colours), as well as the altitude at which the interaction takes place. Green or brownish-red means the sun's particles are interacting with oxygen, “which of course is quite abundant,” while blue or red-coloured lights mean an interaction with nitrogen, McMillan said.
The Northern Lights can also appear in a variety of forms. Sometimes, it can be very stationary, while at other times, there can be lots of movement, and it will appear as if they are dancing across the sky, he said.
The sun's activity is on a cycle, and about every 11 years, there is a peak in solar activity, McMillan said. Right now, solar activity is at a peak, “so we can expect a lot more Northern Lights to occur than we could five years from now, when we'll probably be at another minimum for solar activity.”
The sun is a very dynamic system, McMillan said, “and it's very interesting to study the interactions in our upper atmosphere,” While Science North itself doesn't study aurora borealis, Canada is a leader in its study, and there is a network of cameras around the northern regions that photograph and videotape the auroras for study by scientists.
The topic of aurora borealis is also a good way to remind people that if they take the time to look up at night, they may see some very cool things, he said.
“For me, it really brings home the point that we are part of a much larger universe, and we are affected by it to some degree.”
He said people often ask him whether the aurora happens more often in the winter, but said there is no real correlation between the aurora and the season.
“In the winter, it gets dark so much earlier, and we just happen to be up when it does get dark, so there are many more opportunities to see the aurora. It happens all day long, but we just can't see it when the sun is out.”