The Aurora Borealis or Northern lights are natural light phenomena visible in the night skies within polar regions close to magnetic pole. This beautiful spectacle is caused by particles from solar winds (mainly electrons and protons) colliding with molecules and atoms in the Earth's atmosphere causing them to glow.
This all starts when the Sun sends out some particle known as solar wind into space. These particles can penetrate atmosphere better from the poles where the magnetic field is weaker than at other parts of Earth till they collide with oxygen and nitrogen atoms at high altitudes thereby exciting their molecules to emit colored radiations whose colors depend on gas type and altitude it occurs; for instance oxygen emits green or red light while nitrogen may yield blue or violet light.
Aurora borealis are most common during winter months in places like Scandinavia, Canada, Alaska, and northern Russia; however, occasionally it can be seen even further southward due to very strong solar radiation. It is an amazing phenomenon that often attracts tourists who want to see this celestial spectacle.
Another form of Aurora which appeared during May 2024 was red aurora but it was more intense than usual which meant that it was witnessed beyond its normal territories especially far down Southwards. The red color arises if either particle of solar wind are highly energetic or else encounters with oxygen atoms at higher heights occur.
Appearance of Northern Lights at a Lower Latitude
Appearance of northern lights at more southerly latitudes usually takes place during periods of intense solar activity such as a large solar storm for example. Such occurrences can extend visibility of the Northern Lights into other areas like the south that are out of the normal polar zones. This is a very rare chance to observe this celestial phenomenon so far to the South.
Color of the Aurora Borealis
The color of aurora borealis depends on several factors, including; type of gas in the earth’s atmosphere that collide with solar wind, altitude at which such collision occurs and energy content of particles in solar wind. The following explains how these factors affect color of aurora:
Gas Type
Oxygen
Collisions with oxygen atoms at altitudes between 100 and 300 km cause green light which is also the most common auroral colour. At higher altitudes from about 300 km upwards, oxygen can cause red light though rarely.
Nitrogen
Interactions with nitrogen molecules results into blue or reddish purple colors. When highly energetic solar wind particles are involved, blue color occurs more frequently.
Collision Height
Different colors occur at different altitudes due to variations in atmospheric pressure and composition. Oxygen’s green colour most frequently occurs between 100 km and 300 km, while beyond altitudes above 300 km oxygen may exhibit red colouration. Nitrogen’s blue colour happens even further down.
Particle Energy
Piercingly powerful particles can go down into the atmosphere and encounter molecules at lower heights, which lead to a variety of colors that are explained by different types of collisions.
This is the reason why we see an amazing range of colors during aurora, which means that it results from the intricate interplay between solar wind and Earth’s atmospheric layers. That is why the aurora borealis or northern lights are both beautiful and scientifically stunning.