The Northern Lights

The Northern Lights (Aurora Borealis) are an environmental phenomenon that can be found at the polar regions of the earth called the auroral oval. They are formed as a result of solar winds that interact with the earth’s magnetic field.

Solar Wind: A flow of concentrated charged particles through outer space that originates from the sun.

The sun experiences extremely high heats and pressures at its centre, causing many atoms (protons and electrons) to collide and create explosive reactions and become ejected from the sun’s surface. These particles can then be transported to the earth, which fortunately provides provides protection from them reaching the surface via it's surrounding magnetic field. However, solar winds from the sun are not consistent and can vary due to the rotation of the sun, creating a build up of ionized gas (plasma) in the form of a bubble that can be released; this is referred to as a coronal mass ejection or solar flare.

Coronal mass ejections can carry their own magnetic field as they are travelling through space (This is due to the flow of charged particles which naturally forms a magnetic field; refer to magnetic reversals section). This causes deformations in earth’s magnetic field once these charged particles interact with the planet, which can be referred to as a geomagnetic storm. The charged particles are funneled along the earth’s magnetic field lines to the northern pole and begin to enter the atmosphere. The sudden introduction of charged particles to the atmosphere cause gas molecules to enter an excited state. Once these molecules return to their ground state they emit packets of energy with a wavelength of 390 – 700nm, which is visually seen as colors of violet, blue, green, yellow, orange, and red, therefore creating the northern lights.

Excited state: An energy state of an atom where an electron has retained enough energy to be moved to a higher energy level within the atom, but not completely removed

The colors of the northern lights depend on the gases present in the atmosphere and the altitude at which they occur. Oxygen atoms produce green and red hues, with nitrogen atoms additionally forming red hues and also blue, depending on whether it is in an ionized or excited state. However, the red glow from oxygen is only visible at higher altitudes, where gas molecules are less densely clustered. At lower altitudes, frequent collisions between molecules cause energy exchanges, preventing oxygen from emitting red light. Other northern light colors result from the blending of these atmospheric hues

Ionized state: An energy state of an atom where an electron has retained enough energy to be completely removed from that atom