At the South and North Magnetic Poles of Earth, we see the sky light up, flash and shine. We call this impression Aurora. In the North Pole it’s known as the Aurora borealis, also called the ‘Northern Lights.’ In the South Pole, it’s known as Aurora Australis, also known as the “Southern Lights.”
An Aurora also referred to as a polar light, is a natural light display in the sky, mainly seen in the high latitude (Antarctic and Arctic) regions. Auroras are generated when the magnetosphere is adequately disturbed by the solar wind which the trajectories of any charged particles in both magnetospheric plasma and solar wind, majorly in the form of protons and electrons, precipitate them into the upper atmosphere (exosphere/thermosphere), where their energy is lost. The developed excitation and ionization of atmospheric elements emit light of changing complexity and color. The type of the Aurora, happening within the bands around both the Polar Regions, is also reliant on the amount of acceleration imparted to the precipitating particles. The precipitating protons commonly generate optical emissions as the occurrence of hydrogen atoms after gaining some electrons from the atmosphere. Proton auroras are often observed at the lower latitudes.
The electrons that facilitate the brightest forms of Aurora are properly accounted for their acceleration in dynamic electric fields of plasma turbulence developed during precipitation from the magnetosphere into an auroral atmosphere. On the other hand, static electric fields are incapable of transferring energy to the electrons because of their conservative nature. The ions and electrons which facilitate diffuse aurora seem not to be accelerated during the precipitation. The rise in strength of magnetic field lines directed towards the Earth develops a “magnetic mirror” which turns back most of the downward flowing electrons.
The auroras’ bright forms are developed when downward acceleration not only raises the energy of the precipitating electrons but also lowers their pitch angles (angle between the local magnetic field vector and electron velocity). This significantly raises the deposition rate of energy into the atmosphere, and thereby the rates of excitation, ionization and consequent emission of an auroral light. Also, acceleration raises the electron current flowing between the magnetosphere and atmosphere.
Top 10 interesting facts about the Aurora lights:
1. The Aurora usually occur in the upper atmosphere and are mostly seen at the night in the
Polar Regions.2. The Aurora Borealis is named after a Roman goddess of the dawn -Aurora, and a Greek term for ‘wind of the north,’ Boreas.
3. Green is a highly popular color in the Aurora and is as a result of atomic oxygen at altitudes of between 100 and 200kms.
4. The Aurora on the Saturn is
only visible in an ultraviolet light and can only be seen from space.
5. Red is only visible in the Aurora if the atomic oxygen is produced above 250 kilometers.
6. The aurora light can be a distinct color, based on the kind of gas the plasma mixes with and the height above the surface of the Earth.
7. The Aurora seems to disappear at altitudes of 200-300 km (120-200 miles) above the surface of the Earth.
8. The right place to observe the Aurora borealis is Alaska, United States in the winter months when it’s continuously (24 hours) of darkness.
9. The right place to observe the Aurora Australis is in the Antarctica in the winter months. If the Aurora Australis is powerful, then it can be observed on Stewart Island off the southern coast of New Zealand and Tasmania, Australia.
10. Astronauts working on the International Space Station orbiting Earth at an altitude of 370 km (230 miles) above the Earth at the equal level with the Aurora borealis.
11. In 1989, the Aurora borealis was visible as far south as the island of Cuba and Florida, USA.
12. Aurora also happens on other planets, including Saturn, Jupiter, Neptune, and Uranus.