Around the world the arrival of the New Year is celebrated by massive displays of fireworks, which utilise chemical reactions to produce brightly coloured, sparkling incandescent and luminescent light.
Visible light can be described as electromagnetic radiation that can be perceived by the human eye. The colours of the visible spectrum are red, orange, yellow, green, blue, indigo and violet (in order of longer to shorter wavelengths).
There are two basic types of light sources:
Incandescence - the release of electromagnetic radiation from an object as a result of heat and occurs when atoms are heated and release some of their thermal vibration as electromagnetic radiation. In nature sunlight, starlight and fire are examples of incandescent light.
Luminescence - the release of electromagnetic radiation from an object as a result of chemical, biochemical, or crystallographic changes, the motions of subatomic particles, or radiation-induced excitation of an atomic system.
One of the most spectacular examples of natural luminescent light is the natural polar light display of Aurora Borealis (also known as the Northern Lights) and Aurora Australis.
This phenomenon occurs when solar winds that flow from the Sun, interact with the Earth's atmosphere and its magnetic field. The solar winds contain highly charged particles which travel along magnetic field lines towards the Earth's magnetic poles. As these particles accelerate they collide with atmospheric atoms, molecules and ions.
When energy from the collision is absorbed by an electron of an atom or molecule, this electron moves into a high-energy state and orbits farther away from the atomic nucleus. When the electron falls back into its ground state or low-energy state it releases energy in the form of light. This is known as a photon and it produces light of a certain colour. It is the multitude of photons released in the atmosphere that produce auroras.
The predominant colours that we can see in the auroras, are red, green and violet. When the atmospheric interaction is most dynamic the auroras may appear as twisting arcs, bands, curtains and rays of colour, if the interaction is less active the aurora may appear as a diffuse glow.
Usually auroras are concentrated in two oval areas over the magnetic north and south poles. While the Aurora Borealis can be seen from populated areas in Europe and America, Aurora Australis occurs mainly over the uninhabited regions of the Antarctic. It can regularly be observed faintly from Tasmania, but is only seen very infrequently from mainland Australia, South America and South Africa.
However the auroral ovals are not static and expand in response to solar storms, which follow an 11 year cycle. In 1859 a huge solar storm hit Earth and enveloped most of the planet in a brilliant aurora that in some areas turned night into day. In Australia auroras were reported in the skies over Brisbane, so we know that the night skies over Tamborine Mountain have, for a few nights at least, shimmered with the spectacular beauty of Aurora Australis.