What are the different colours of the Northern Lights?
The Northern Lights, also known as the Aurora Borealis, are one of the most spectacular natural phenomena that occur in the northern hemisphere. The bright, colourful lights dancing across the sky have captivated people for centuries, and scientists have been studying them for just as long. One of the most fascinating aspects of the northern lights is their colour. In this blog post, we will explore what determines the colour of the northern lights.
The northern lights are caused by particles from the sun colliding with the Earth’s magnetic field and atmosphere. These particles are mostly electrons and protons, which are accelerated by the sun’s magnetic field and sent hurtling towards the Earth. When they reach the Earth’s magnetic field, they collide with the atoms and molecules in the atmosphere, exciting them and causing them to emit light.
The colour of the northern lights depends on the type of atom or molecule that the particles collide with. The most common colour of the northern lights is green, which is caused by collisions with oxygen atoms in the Earth’s atmosphere. When an electron collides with an oxygen atom, it excites the atom, causing it to release a photon of green light. This is why the northern lights often appear green in colour.
However, other colours can also be seen in the northern lights. For example, collisions with nitrogen molecules can produce red and purple colours, while collisions with oxygen ions can produce blue and purple colours. The exact colour of the northern lights can also be influenced by the altitude at which the collisions occur. For example, collisions with oxygen atoms at higher altitudes can produce a deep red colour, while collisions with nitrogen can produce a violet colour at lower altitudes.
The strength and frequency of the collisions can also affect the colour of the northern lights. When the particles from the sun collide with the Earth’s atmosphere more frequently and with greater energy, they can produce brighter and more vivid colours. This is why the northern lights can appear more intense during periods of high solar activity, such as during a solar storm.
In conclusion, the colour of the northern lights is determined by the type of atom or molecule that the particles from the sun collide with, as well as the altitude, strength, and frequency of the collisions. While green is the most common colour of the northern lights, a range of other colours can also be seen, creating a breathtaking display of natural beauty in the night sky.