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How & When Does Northern Lights Happen? The Science

how and when do the northern lights happen

The Northern Lights are one of the most beautiful natural phenomena on Earth. But how and when does Northern Lights happen? What causes them and why?

In this article, we’ll take a look at the science behind these amazing lights, to give you an idea of when you’re most likely to see them.

If you are planning a holiday to see the extraordinary aurora for yourself, you should take some time to understand the science behind why and when the Northern Lights occur.

This will help you to read and understand aurora forecasts, and ensure that you plan your holiday in such as way that you’ll have the best chance of seeing the lights.

What are the Northern Lights?

The Aurora Borealis, also known as the Northern Lights, is a natural phenomenon that happens on Earth. It is caused by an interaction between the sun’s ultraviolet light and Earth’s atmosphere. This causes energy to be released, which creates beautiful lights in the sky.

The phenomenon is referred to as the Aurora Borealis (Northern Lights) when it occurs in the northern hemisphere and the Aurora Australis (Southern Lights) when taking place within the southern hemisphere.

When talking about Northern Lights we are referring to Polar Aurora (source: World Meteorological Organization).

Polar Auroras (Aurora Borealis, Aurora Australis)

Polar Auroras are what is commonly known as the Northern Lights (or Southern Lights).

They are one of the most beautiful things to see in the sky. They’re an amazing display of light that can be seen when the Earth’s magnetic field lines intersect with the plasma (a gas made up of electrons and protons) in the upper atmosphere. The result is a colorful ring around the North Pole.

Polar auroras are found near the poles at high latitudes, and are very bright. These auroras are most visible during the night, but they can also be seen during the day. They usually last for around an hour, but sometimes they can last for up to several days.

STEVE phenomenon

A less common light spectacle similar to Auroras is STEVE (Strong Thermal Emission Velocity Enhancement). While STEVE appear similar to aurora, they are a different phenomenon. They occur when charged particles from the sun interact with the Earth’s atmosphere. This interaction creates a variety of colors, but most often pink, purple and green. While auroras are typically seen at high latitudes (close to the poles), it is possible to view STEVE in other locations at lower latitudes. (Source:

What causes the Northern Lights?

The Northern Lights and Southern Lights that we see in the night sky are really the result of activity that is occurring on the surface of the sun. This is why it is useful to learn about solar activity, and how solar activity triggers Northern Lights to happen on Earth, if you are interested in chasing the aurora.

First, solar storms…

It all begins on the sun. Large clouds of electrically charged particles (protons and electrons) are sent into space when solar storms roil the surface of our sun. These particles are capable of traveling millions of kilometers at incredibly fast speeds, and a small portion of them reach the Earth. This barrage of particles is called Solar Wind.

The solar wind travels at speeds of around one million miles per hour, and the particles take approximately 40 hours to reach our planet after leaving the sun.

Next, particles come to Earth…

The magnetic field of the Earth deflects around 98 percent of these particles, which then continue on their trip into the depths of space.

However, a small percentage are pulled into the magnetic field of the Earth. These particles are then directed towards the magnetic poles of the Earth’s North and South Poles. Because of this, the majority of auroral activity may be seen near the magnetic poles.

Then particles, atoms and molecules collide… and make light!

Once they reach the poles, these charged particles cause collisions with atoms and molecules located high up in our atmosphere. These collisions result in the formation of two brilliant rings of auroral emission known as auroral ovals, which are seen around the North and South magnetic poles.

What we are seeing with the Northern Lights is the collision of particles from the Sun with atoms and molecules that are present in our atmosphere. The wavy patterns and light “curtains” that are distinctive of the aurora are created by the lines of force that are present in the magnetic field of the Earth.

Tom Kerss, an astronomer at the Royal Observatory, says that when these particles collide with atoms and molecules in the Earth’s atmosphere, they basically heat up the target particles. This physical process, which we refer to as “excitation,” is quite similar to what happens when you heat up gas and make it light.

The portion of an aurora that is closest to the ground is normally located around 130 kilometers (80 miles) above the surface of the earth. On the other hand, the very peak of a show may be located several thousand kilometers above the surface of the Earth.

Where and when does Northern Lights happen?

Auroras are most commonly known as the colorful lights in the sky that we see during wintertime, typically near the North Pole. The aurora are less commonly seen near the South Pole; not because they occur less around the South Pole, but rather there is less land around the Antarctic Circle that people can visit and see it from, unlike in the North.

While the Northern Lights can happen any month of the year, they are most visible in late winter and early spring. They usually start to be seen around December and January, and peak around February and March. Different locations around the world report different times of year as being good for viewing auroras, something that we discuss in more detail in other articles. To learn more, check out our article about the best time of year to see Northern Lights around the world.

How does solar activity influence when Northern Lights happen?

Aurora borealis (and aurora australis in the Southern Hemisphere) are caused by charged particles (ions) entering Earth’s atmosphere from space, via solar winds. These particles collide with oxygen and nitrogen atoms in the atmosphere, creating light. This process happens mainly during periods of high solar activity (like when there are lots of sunspots), though it can also happen during low solar activity periods too.

Solar wind is always present, but it increases and decreases in intensity in accordance with what we call Solar Cycles. Each solar cycle lasts around 11 years, and when it is in the peak (that is, there is a high level of solar activity) the auroras are said to be more intense. You can read more about the best years for planning a vacation to see the Northern Lights according to the next solar cycle peak in our article here.

The Northern Lights come about as a result of the interaction of solar winds with the various components that make up a planet’s atmosphere, centralized around the Earth’s magnetic poles.

Therefore, the best places to see the aurora is at high latitudes, close to either the north or south magnetic pole. In other words, near and within the Arctic Circle (66°30’ N) in the Northern Hemisphere, and the Antarctic Circle (66°30’ S) in the Southern Hemisphere.

History of the Northern Lights

The word “aurora borealis” was first used in 1619 A.D. by Galileo Galilei, who named it after Aurora, the Roman goddess of the dawn. He was under the mistaken impression that the auroras he saw were caused by the reflection of sunlight from the atmosphere.

In the year 1790, Henry Cavendish carried out observations of the aurora that could be quantified. He employed a method that is known as triangulation to arrive at his conclusion that the light from the aurora is created somewhere between 100 and 130 kilometers in height, which is about 60 miles above the surface of the Earth.

Based on the results of his “terrella experiment,” a Norwegian scientist named Kristian Birkeland came to the conclusion in 1902 and 1903 that the light of the aurora borealis was created by currents moving through the gas in the upper atmosphere. The operation of neon light in the current day is precisely like this.

Where can I learn more about the science of Aurora Borealis?

Aurora Borealis (Aurora Borealis, Northern Lights) is one of the most impressive natural phenomena in the world. The science of Aurora Borealis is complex and fascinating, but luckily, there are plenty of resources available to help you learn all you need to know about it.

Two excellent sources for easy-reading information about Aurora Borealis can be found at and NASA. Meanwhile, the Space Weather Prediction Center (SWPC / NOAA) is recommended for more scientific and technical data on aurora borealis.

Scientific organizations and institutes in various countries often have a branch dedicated to the study of space phenomenon including the aurora, which are excellent sources of scientific information and data.

How and when Does Northern Lights happen? Conclusion

If you’re interested in witnessing the awe-inspiring Northern Lights, then you’ll want to be well-informed about the science behind their occurrence. In this article, we have explained the science behind how and when the Northern Lights happen to help you plan your Aurora viewing place and time properly. You should now have a good understanding of how the Northern Lights work from a scientific perspective, which will in turn help you understand Aurora forecasts and choose suitable locations, if you plan on traveling to see these mesmerizing lights in person!

How and when does Northern Lights happen | Article Sources

Dr Melanie Windridge. 2017. Aurora: In Search of the Northern Lights (Paperback).

National Geographic

World Meteorological Organization

Australian Academy of Science

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