Stargazing: Understanding the Northern Lights

Stargazing: Understanding the Northern Lights

Ken Tapping, astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory

My very first encounter with an aurora was in England, before I came to Canada, at the house of a radio amateur.

He was communicating by sending shortwave signals northward, where they reflected off an aurora to radio amateurs all over northern half of our planet. The Morse Code bouncing back from the aurora was really strange. The whistle notes making up the dots and dashes had a strange “warbling” tone and sounded as though they were echoing in some vast, celestial cathedral. It was much more fascinating than the only sighting I had of an aurora from southern England, an elusive green glow in the northern sky that went away after a couple of hours. Then I saw the Canadian version.

In Canada, particularly in the North, the aurora can be truly spectacular: flickering curtains, blobs and rays of green and red, and sometimes bright enough to read by. It’s not surprising that most northern communities around the world have incorporated the northern lights into their mythology and folk lore. There is far too much to summarize here, but two contrasting myths are: don’t look at the aurora while giving birth or your child will be cross-eyed, alternately, children conceived under the aurora will be exceptional.

Scientists have been trying to work out what an aurora is and how it works for well over a hundred years. We now know roughly what is going on, but there are still lots of fundamental things we do not understand. We know for sure that auroras are caused by interactions between the sun, the Earth’s magnetic field and the atmosphere.

The story starts with the solar wind, a blast of atomic particles and magnetic fields flowing out from the sun. It is always there, but varies in speed and density, becoming a solar gale on occasion. Most of the time it is flowing at a few hundred kilometres a second, but sometimes comes at us at thousands of kilometres a second.

The Earth is surrounded by a magnetic field. In the absence of the solar wind it would appear like a huge doughnut, with the holes centred over the north and south magnetic poles. However, the solar wind blows it out into a long, teardrop shape.

Particles from the solar wind are constantly penetrating the Earth’s magnetic field and getting trapped there. The rubbing of the solar wind over the surface of the Earth’s magnetic field makes waves. These run along the magnetic field, down to the ground at northern latitudes. These can be picked up and converted to sound. They sound like “feeding time at a cosmic zoo.”

When the solar wind blows extra hard, more of the Earth’s magnetic field is pushed back into the tail of the teardrop. This drives the stresses higher in in a place that is already highly unstable. The magnetic fields snap, releasing their stored energy. The energy pulses propagate back towards the Earth, where they accelerate particles down into the atmosphere around the magnetic poles, where they collide with atoms of nitrogen and oxygen in the air, making them glow green and red. The sheer variety in auroral displays is due to the range of processes involved, because each may manifest itself in different ways. Space missions have shown that other planets with magnetic fields have auroral displays too.

The beautiful light show is only a tiny part of what is going in the upper reaches of our atmosphere. Huge electric currents are flowing, a menagerie of plasma waves are growing and spreading out, and magnetic fields are doing amazing things. It is intriguing to think that some of the most challenging physics in the universe is going on a few hundred kilometres above our heads.

Venus shines brightly in the west after sunset. After dark, Jupiter dominates the southern sky and Saturn is rising in the southwest. Mars rises about 1 a.m. The moon will be new on June 13.

Ken Tapping is an astronomer with the National Research Council’s Dominion Radio Astrophysical Observatory, Penticton.


Steve Kidd
Senior reporter, Penticton Western News
Email me or message me on Facebook
Follow us on Facebook | Twitter | Instagram

Just Posted

Scooters lined up for an educational event in Stuart Park on Wednesday, June 16. (Amandalina Letterio/Capital News)
Free e-scooter safety training in Kelowna

Shared e-scooter operators collaborate to educate riders

The suspect reportedly assaulted a security guard and robbed him. The incident happened at a Kelowna hotel. (Contributed)
Okanagan Lake (File photo)
Thompson-Okanagan ready to welcome back tourists

The Thompson-Okanagan Tourism Association expects this summer to be a busy one

Employees at Playtime Casino wait outside while firefighters inspect the building after a small storage room fire on Wednesday, June 16, 2021 (Amandalina Letterio/Capital News).
Small fire at Kelowna’s Playtime Casino as staff preps to re-open

Fire ignited in the storage room, but the staff were able to put it out

Maxwell Johnson is seen in Bella Bella, B.C., in an undated photo. The Indigenous man from British Columbia has filed complaints with the B.C. Human Rights Tribunal and the Canadian Human Rights Commission after he and his granddaughter were handcuffed when they tried to open a bank account. THE CANADIAN PRESS/HO-Heiltsuk Nation, Damien Gillis, *MANDATORY CREDIT*
VIDEO: Chiefs join human rights case of Indigenous man handcuffed by police in B.C. bank

Maxwell Johnson said he wants change, not just words, from Vancouver police

A mother stands with her daughter, visiting senior parents but observing social distancing with a glass door between them.  The granddaughter puts her hand up to the glass, the grandfather and grandmother doing the same.  A small connection in a time of separation during the Covid-19 pandemic (Valley First/Contributed).
Have your say on which Okanagan, Thompson, Similkameen charities get donation

Valley First seeks public help to distribute $250,000 to local charities via social media campaign

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Tk’emlups te Secwepemc Chief Rosanne Casimir stands outside the former Kamloops Indian Residential School after speaking to reporters, in Kamloops, B.C., on Friday, June 4, 2021.THE CANADIAN PRESS/Darryl Dyck
Kamloops chief says more unmarked graves will be found across Canada

Chief Rosanne Casimir told a virtual news conference the nation expects to release a report at the end of June

Vernon Courthouse. (Jennifer Smith - Morning Star)
Sentencing delayed in North Okanagan child pornography case

Man who pleaded guilty to possessing child pornography will have new sentence date fixed next week

A woman wears a vaccinated sticker after receiving a COVID-19 vaccine at a vaccination clinic run by Vancouver Coastal Health, in Richmond, B.C., Saturday, April 10, 2021. THE CANADIAN PRESS/Jonathan Hayward
B.C. ranks among highest in world in COVID-19 first-dose shots: health officials

More than 76% of eligible people have received their 1st shot

People decided to tag Skaha Bluffs rocks which the Ministry has to go in and now clean up. (Facebook)
Bluffs at popular Penticton rock climbing park defaced

Ministry of Environment is going to clean it up

A screenshot of the First Peoples Cultural Councils First Peoples’ Map. (First Peoples Cultural Council)
Online resource blends B.C.-Alberta’s Indigenous languages, art and culture

Advisor says initiative supports the urgent need to preserve Indigenous languages

Most Read