Imagine the sky opening up into curtains of green light that ripple like fabric in the wind. It is not fire, it is not a reflection. It is the aurora: one of the most impressive spectacles nature offers, and one of the best explained by science.
The aurora is neither magic nor coincidence. It is the result of an encounter between the Sun, our own Earth and an invisible shield that protects life every single day. When you understand how it works, the glow becomes even more impressive.
In this article you will discover where this light comes from, why it has different colors, and why it sometimes appears even in the far south of Brazil. And, in the end, why so many people look at it and think of something greater.
It all begins in the Sun
The aurora begins 150 million kilometers from here, in the Sun. Our star is not still and quiet. It boils, explodes and constantly releases a stream of energy-charged particles. That stream has a name: the solar wind.
The solar wind is made of tiny bits of matter, mainly electrons and protons, traveling through space at more than a million kilometers per hour. It blows in every direction, and part of it comes straight toward us.
Sometimes the Sun releases a much stronger burst, called a solar storm. It is as if it let out a giant sneeze of particles. When that burst reaches us, that is when the auroras grow stronger and can appear in places where normally no one sees them.
Think of it this way: without the Sun releasing this wind, auroras simply would not exist. The aurora is the luminous signature of our Sun touching our planet.
Earth's invisible shield
If the solar wind struck the surface of the Earth directly with no barrier, life as we know it would be very difficult. But the Earth has a shield: the magnetic field, generated by the molten iron spinning in the planet's core.
This magnetic field wraps the whole Earth like a giant, invisible bubble, called the magnetosphere. When the solar wind arrives, most of it is deflected, sliding around the bubble like water flowing around a rock in a river.
But the magnetic field is not closed evenly everywhere. Near the north and south poles, the magnetic lines dive toward the ground. It is there that some particles manage to descend and enter the atmosphere. That is why the aurora happens near the poles, and not along the equator.
This shield works in silence all day long, protecting you without anyone noticing. The aurora is, in a way, the visible proof that it is there, doing its job.
Where the light really lights up
The particles that descend through the poles go on to strike the air way up high, in a band that runs from about 100 up to 300 kilometers in altitude. To give you an idea, a commercial airplane flies at about 10 or 12 kilometers. The aurora happens much, much higher.
Up there, the air is thin, but there are still oxygen atoms and nitrogen molecules floating around. When a solar wind particle strikes one of those atoms, it hands over energy to it. The atom becomes 'agitated', or, as scientists say, excited.
The atom does not like to stay agitated for long. Very quickly it releases that extra energy in the form of a tiny drop of light. Multiply that by trillions of atoms glowing at the same time, and you have an entire curtain of light covering the sky.
It is the same principle as a neon lamp or those colorful store signs: gas excited by energy gives back light. The aurora is a giant, natural neon sign, the size of a country.
Read alsoThe phases of the moon explainedWhy the aurora has different colors
The color of the aurora depends on two factors: which gas is glowing and at what height. Each gas has a favorite color, as if each one sang a different note.
Oxygen is the one mainly responsible for the most famous colors. At a medium height, between 100 and 150 km, it glows green, the most common aurora color. Much higher, above 200 km, oxygen releases a deep red, which is rarer and harder to see.
Nitrogen makes up the other team of colors. In the lower layers, it produces shades of blue, purple and even pink at the edges of the curtains. It was precisely a purplish tone that appeared in the south of Brazil during some recent solar storms.
Here is a simple table to keep in mind:
| Color | Gas | Approximate height |
|---|---|---|
| Green | Oxygen | 100 to 150 km |
| Red | Oxygen | above 200 km |
| Blue and purple | Nitrogen | 80 to 100 km |
So, the next time you see a photo of an aurora, you can read the sky like a map: green at the bottom, red at the top, purple at the edges.
Northern lights in the north, southern lights in the south
Because the aurora happens near both poles, it earned two names. In the northern hemisphere, it is called the aurora borealis, which comes from Boreas, the name of the north wind in Greek mythology. It is the one you see most in photos, in Norway, Alaska, Iceland and Canada.
In the southern hemisphere, the phenomenon is exactly the same, only it receives the name aurora australis, from 'austral', which means of the south. It lights up skies near Antarctica, southern New Zealand and southern Argentina and Chile.
Most of the time, Brazil is too far from the poles to see the aurora. But during very strong solar storms, the phenomenon spreads to lower latitudes. In January 2026, during one of the most intense solar storms in decades, a purplish band was recorded in the sky over Rio Grande do Sul.
Honesty is worth it here: these appearances in the far south of Brazil tend to be faint, often visible only in long-exposure cameras, and not with the same intensity as the polar auroras. Even so, it is thrilling to know that the same light from the Arctic has already touched the Brazilian sky.
The Sun has an 11-year rhythm
The Sun does not always release the same amount of energy. It has a rhythm, a cycle that lasts on average 11 years. In this cycle, solar activity rises to a peak, called solar maximum, and then falls to a calmer period.
During solar maximum, the Sun becomes covered with spots and releases many more storms. It is in this phase that the auroras become more frequent, brighter and reach places farther from the poles. That is why sky observers keep an eye on the solar calendar.
Solar cycle 25, which we are living through now, reached its maximum around 2024 and 2025, and that is why the last few years have had so much news of auroras appearing in unusual places. It is a good moment in history to take an interest in this subject.
If you want to put this into practice in the Club, you can arrange with the Counselor to follow space weather forecast sites and plan an observation. Astronomy and patience go together, and the result is worth the wait. See also our guide on how to observe the night sky and the Astronomy Honor.
Looking up and seeing more
Many people, when they see an aurora, feel something hard to put into words. It is the sense of standing before something great, beautiful and ordered. You do not have to be religious to be moved by it. But, for us Pathfinders, that emotion also points in a direction.
The Bible, thousands of years ago, was already inviting people to look at the sky and read a message in it. Psalm 19:1 says: 'The heavens declare the glory of God; the skies proclaim the work of his hands' (NIV). The sky, for whoever wrote this, was a sermon without words.
Curiously, the book of Job, one of the oldest in the Bible, makes an observation that fits the aurora: 'Out of the north comes golden splendor; God is clothed with awesome majesty' (Job 37:22, NIV). It is as if the author had already noticed that the great glows in the sky tend to come from the north.
And Isaiah 40:22 describes God as the one 'who stretches out the heavens like a canopy, and spreads them out like a tent to live in' (NIV). A tent, a canopy. The same imagery of a spread curtain that scientists use today to describe the rippling shape of the aurora. As Adventists, we believe that nature is a second book that speaks of the Creator. You do not have to agree with this to appreciate the science, but the invitation to reflect remains. If you want to go deeper, see what faith is.