Northern lights a reminder of the sun’s influence on Earth | CBC Radio

A flare there erupted on the sun this week should give a show of Northern Lights to many parts of the country this weekend. The beautiful northern lights are a visual reminder that the sun floods our planet with more than just light and heat.

Our star, the sun, is a fundamental supplier of energy to the earth, scattering light, driving the weather and feeding green plants. Life could not exist here without it.

But the glowing ball we see crossing our sky every day is just the visible part of the sun. Other forms of radiation we do not see shoot away from the surface, along with a constant wind of charged particles that wash over the earth and the other planets in the solar system. So in a way, we live in the sun.

The sun is an incredibly powerful nuclear furnace, with energy and hot gases bubbling up from its interior, like boiling soup, which is sometimes concentrated in sunspots. These can accumulate and produce powerful loops of magnetic energy.

Sometimes these loops become strained and burst, emitting a bright flame of powerful X-rays, often accompanied by what is called a coronal mass ejection, a huge sphere of plasma – or superheated electrified atoms – that is ejected into space like a tornado out of a thunderstorms.

This image from January 2003 from the International Space Station shows the northern lights over Canada with the impact crater Manicouagan in the foreground. (NASA / AFP via Getty Images)

When one of these eruptions points to the earth, which happened this week, we see the effects in space and on the ground. In March 1989, a super-powerful lump hit the Earth’s magnetic field. This generated electrical surges in ground power lines that shortened the entire power grid in Quebec and parts of the northeastern United States. Since then, the electricity companies have tightened their systems to try to prevent similar power outages in the future.

Satellites have been knocked out of operation by electrical disturbances from solar storms. They have also been knocked out of orbit when the sun’s activity inflates our atmosphere, causing drafts that slow down the spacecraft.

And speaking of the atmosphere, the ionosphere – the electrically charged upper layer of our atmosphere – can be disturbed by solar flames, interrupting certain radio communications that use that layer to bounce signals around the earth. Astronauts aboard the International Space Station have been asked to temporarily move to the central core for X-ray protection during intense solar storms.

Although solar storms can disrupt our technology, they do not pose a direct threat to us on the ground, thanks to the protection provided by the earth’s magnetic field. Particles from the sun do not reach the surface. Instead, they follow the magnetic field towards the North and South Poles, where they interact with the atmosphere and give us the spectacular celestial light show of the Northern Lights, or Aurora Borealis in the northern hemisphere and Aurora Australis in the south.

Large light curtains, sometimes draping across the sky from horizon to horizon, glow in different colors depending on how different gases in the atmosphere are set glowing at different heights. Green is most common, from oxygen, while nitrogen produces red. The lights seem to reach all the way to the ground, but in reality all activity takes place about 100 kilometers up. This means that the lamps are safe to look at.

Aurora is a permanent feature on Earth as well as other planets with magnetic fields, such as Jupiter and Saturn. They form glowing rings around the posts like jeweled crowns. But when the sun gives off an explosion of activity, the rings are pushed towards the equator, which in Canada means that more densely populated regions in the south can see them.

So if you have clear skies the next few nights, find a dark place and look at the sky. If you watch the light show, think about the fact that you are watching the effects of a storm that took place 150 million kilometers away on the rolling surface of our star.


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