Why northern lights didn't dazzle most Canadians
Solar phenomenon failed to align with Earth's magnetic field, NASA expert says
Most of Canada did not see the spectacular northern lights show that was predicted to make its way across the country last night. The lights, also known as the aurora borealis, were expected to appear at 3 a.m. ET in areas as far south as Oregon.
“People were predicting a major display. My understanding is that it wasn't really anything special,” said Larry Kepko, a research astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It was a fairly typical night of northern lights."
If the northern lights had displayed across all of Canada last night, as was hoped, they would have been bright enough to be seen even in large cities. The lights are usually a rural phenomenon.
Kepko said astronomers predicted a significant display because, on Tuesday, a mass of solar energy erupted from the sun. This solar eruption, known as a coronal mass ejection (CME), was headed toward earth at 500 km/s.
The dancing lights that typically appear in northern regions are displayed when charged particles from the sun interact with Earth's magnetic field, so the solar eruption could have created great conditions for northern lights.
'Solar maximum' period
“We know something is coming. We don’t know how this something is going to impact Earth’s magnetic sphere," Kepko said. "It could be pretty serious, it could cause aurora, or it could cause nothing.”
This time, it caused nothing.
It was a fairly typical night of northern lights.- Larry Kepko, NASA astrophysicist
That's because the magnetic field from this particular solar event did not match up with the Earth’s.
When they do match up, light is emitted and the northern lights blaze across the sky.
Kepko said that this year and for the next few years, we will be at our "solar maximum" — a period of solar activity that occurs every 11 years. During this time one can expect to see aurora borealis almost every night in the auroral zone, which runs through places like Alaska, Greenland, Iceland, and parts of Canada.
“Any average night during solar maximum you might see one or two auroral displays. They’ll be nice. They’ll maybe last about 15 minutes, and then they’ll die out,” Kepko said. But when a CME interacts with earth, it is a totally different experience. He analogizes it with skiing down a small hill versus skiing in the Swiss Alps.
“It might last six hours or 10 hours. It’s brighter. It fills the entire sky. It’s much more dynamic. It’s constantly changing,” he said. “Until you see it, it’s hard to explain how different it is.”