Sun entering “active phase”; Earth’s magnetic field protects us while putting on a show
By Lawrence Belanger
Local Journalism Initiative
The Northern Lights have been spotted in the Townships recently, an unusual occurrence this far south in Canada. After photos circulated online of the aurora borealis over Tompkins Creek in Ogden, The Record sat down with Dr. John Ruan of the Bishop’s University’s Physics & Astronomy Department, to understand why they were visible so far south last week.
“There is an 11-year solar cycle where the sun’s activity will increase and then decrease,” details Ruan. He goes on to explain that the sun is entering an “active phase”, resulting in the increased ejections of magnetically-charged particles into the solar system. This activity also comprises magnetic fields that contain a lot of energy, and sometimes they “reconfigure” themselves. Ruan explains that when they do, they eject a lot of particles. “These are very high-energy particles,” remarks Ruan.
After the sun ejects these particles, they travel through the solar system, and sometimes Earth is in their path. “When they hit Earth, Earth’s magnetic field redirects them towards the magnetic poles,” explains Ruan. With the increased frequency and amount of particles from the sun during this phase, the phenomenon is visible further south (or north).
But what causes the northern lights, also known as the aurora borealis, and their less-known sibling, the southern lights, or the Aurora Australis, to appear at all?
“The reason why you see these northern and southern lights,” Ruan explains in his office, is because of how Earth’s magnetic poles redirect the particles to the north and south. These magnetic poles, located in the Arctic and Antarctic respectively, form a magnetic field over the Earth that protects the atmosphere from these coronal ejections from the Sun.
“When these charged particles get redirected to the north and south poles, they…essentially hit [different] particles in the atmosphere.” These reactions produce visible light and have been observed by humans since ancient times. Without this field, Ruan says that Earth’s atmosphere would get “blown away” by these ejections, causing it to resemble the next planet on the way out of the Solar System, Mars. “Mars doesn’t really have much of an atmosphere,” says Ruan. “Part of that is because Mars doesn’t have a strong magnetic field,” so when the sun spews particles towards it, they bombard the planet directly.
“You might have seen images of the surface of Mars…where you actually can see dried riverbed. That’s because Mars used to have running water,” explains Ruan. With its weaker magnetic field, the planet’s atmosphere was blown away by cumulative solar activity.
Although Earth’s magnetic field protects its atmosphere, human activity can be impacted by solar ejections. Most famously was the “Carrington Event”. In 1859, the largest coronal mass ejection knocked out telegraphs across the world. More locally and recently, a geomagnetic storm in 1989 knocked power out across the province. “I think it knocked out power for about 6 million people in Quebec,” recalls Ruan. “It caused a scandal for Robert Bourassa’s government,” since people didn’t entirely understand what caused the power outage.
Ruan warns that, if it happened today, the impact could be magnitudes higher.
“Everything would be down,” says Ruan. “There’d be no internet, there’d be no power. Everything would be down for months.” Luckily, there is some level of advanced warning. “It takes some time for these particles to travel to Earth,” which is not very long, but still not instant. Additionally, similar to how seismic activity can often presage stronger tremors of an earthquake, scientists can observe increased solar flares on the sun before they lead to an ejection.
The maximum of the sun’s cycle, when the sun is most active, is coming up in 2025, but the rates of coronal mass ejections are expected to increase, meaning the auroras should be visible further south than usual, culminating in 2025. Curious stargazers can find out when future events will happen by checking spaceweatherlive.com, which details solar and auroral activity. Just remember, the light show is also protecting all life on the planet from the void of space.
