The Northern Lights are a reminder of the Sun’s influence on Earth

A rocket that burst on the sun this week should bring a show of northern Lights in many parts of the country this weekend. Beautiful auroras are a visual reminder that the sun floods our planet with more than just light and heat.

Our star, the sun, is a fundamental provider of energy for the Earth, providing light, controlling the weather and nourishing green plants. Life could not exist here without it.

But the luminous ball that we see crossing our sky every day is only the visible part of the sun. Other forms of radiation that we don’t see bursting from the surface, as well as a constant wind of charged particles sweeping across Earth and the other planets in the solar system. So, in a sense, we live inside the sun.

The sun is an incredibly powerful nuclear furnace, with energy and hot gases bubbling from its interior, like boiling soup, which sometimes concentrate in sunspots. These can cluster together producing powerful loops of magnetic energy.

Sometimes these loops become taut and burst, releasing a bright burst of powerful X-rays, often accompanied by what’s called a coronal mass ejection, a huge blob of plasma – or superheated electrified atoms – that is blasted into the space like a tornado out of a thunderstorm.

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

When one of these flares is directed at Earth, as happened this week, we see the effects in space and on the ground. In March 1989, a super powerful drop hit the Earth’s magnetic field. This generated electrical surges in ground power lines that shorted out the entire power grid in Quebec and parts of the northeastern United States. Since then, electric utilities have beefed up their systems to try to prevent similar outages in the future.

Satellites have been knocked out of service by electrical interference caused by solar storms. They’ve also been pushed out of orbit as activity from the sun swells our atmosphere, causing drag that slows spacecraft.

And speaking of the atmosphere, the ionosphere – the top electrically charged layer of our atmosphere – can be disrupted by solar flares, disrupting some radio communications that use this layer to bounce signals around the Earth. Astronauts aboard the International Space Station have been asked to temporarily move to the central core to protect against X-rays during intense solar storms.

While solar storms can disrupt our technology, they don’t threaten us directly on the ground, thanks to the protection afforded by the Earth’s magnetic field. Sun particles do not reach the surface. Instead, they follow the magnetic field to the north and south poles, where they interact with the atmosphere giving us the spectacular celestial light show of the Northern Lights, or Aurora Borealis in the northern hemisphere and Aurora Australis in the South.

Vast curtains of light, sometimes draping the entire sky from horizon to horizon, glow in different colors depending on how different gases in the atmosphere are ignited at different altitudes. Green is the most common, from oxygen, while nitrogen produces red. The lights seem to reach down to the ground, but in fact all the activity is about 100 kilometers away. This means the lights can be safely monitored.

Auroras are a permanent feature of Earth as well as other planets with magnetic fields, such as Jupiter and Saturn. They form luminous rings around the poles like jeweled crowns. But when the sun gives off a burst of activity, the rings are pushed towards the equator, which in Canada means more densely populated areas to the south can see them.

So if you have clear skies over the next few nights, find a dark spot and look up. If you see the light show, think about the fact that you are watching the effects of a storm that occurred 150 million miles away on the choppy surface of our star.


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