One of the most beautiful natural phenomenons on our planet are aurora’s; Aurora Borealis (Northern lights) and Aurora Australis (Southern lights). For those unaware, aurora’s are events that occur at high latitude (Antarctic and Arctic areas) and occurs due to the disruption of the magnetosphere. Lets have a look at the solar activity responsible for generating these absolutely stunning light shows!
The Earth has a classifications of spheres around it that is determine due to different characteristics. One of these ‘layers’ is known as the magnetosphere and is the magnetic field around Earth in which charged particles are disrupted. The side of the magnetosphere that faces the sun is compressed (as seen below) because of the bombardment of solar winds that travel up to speeds of 1,500,000km/hr. The magnetosphere is an invisible protective layer that redirects high energy radiation around and away from the planet ensuring a somewhat constant environment for us with minimal exposure. Why it is there around Earth, Mercury and all other gas planets is unknown but we do know that it has something to do with the interaction between the inner (solid nickel-iron alloy) and outer core (liquid iron and nickel mixture) of our planet. This interaction causes large and complex patterns of electrical currents that stabilizes and protects use; this is called the dynamo.
There are a couple ways in which auroras can occur with some being more powerful than others depending what causes them. The most consist way is due to the continuous ‘pour’ of radiation from the sun and from the outer reaches of the universe (cosmic radiation). Stronger auroras occur due to increased solar activities like solar flares and coronal mass ejections (CMEs) where the magnetosphere is bombarded with more high energy particles and radiation, increasing excitation of upper atmospheric atoms. It is events like this in which auroras like Aurora Australis was visible to spectators as far northwards as Auckland; which is uncommon.
This radiation interacts with atoms in the Earth’s upper atmosphere moving them into a higher-energy states because of the additional energy (atoms vibrate faster). Once the radiation temporarily stops interacting with the atom, it moves back into a lower energy state and the extra energy is lost in the form of light (a photon). Green is the most common of colours viewed but you can also witness red (only during intense solar activity), blue and purple (highest solar activity), ultraviolet and infrared (invisible to the human eye) and rarely yellow and pink. The colours visible is determined by variables like altitude and how particles of oxygen and nitrogen interact with one another. Not only colour and the invisible ultraviolet and infrared but X-rays have also been detected discovered in 1972 as well as a noise that sounds like hissing in the upper atmosphere.
Not only are they present on Earth but also on some of the other planets in the solar system; Jupiter, Saturn, Uranus and Neptune. Regardless of the planet or where they are view from, being Earth or from the Hubble Telescope, auroras are breathtakingly stunning and the viewing of such an event is definitely on my bucket list.