Aurora Borealis, also referred to as sometimes the northern lights or, also by the name of polar lights is a magnificent phenomenon viewable at high latitude regions near Arctic and Antarctica.

Auroras occur due to disturbances in the magnetic environment of the sun, often referred to as the magnetosphere. The magnetic field lines present around the sun carries energy from the interior of the sun to outside it. However, sometimes due to disturbances in the magnetosphere of the sun, these magnetic fields often release a stream of charged particles in the dark void of space often known as solar winds. There is a constant stream of these solar winds from the sun. But during one kind of storm known as Coronal Mass Ejection (CME), the sun ejects a bubble of the stream of electrified particles traveling through the vacuum of space at high speeds towards the Earth.

The Earth also has a magnetic field present around it which deflects off charged particles coming from the sun and other cosmic phenomena. When a CME interacts with the magnetosphere of the Earth, some particles travel along the magnetic field lines to the North and South Pole. The resulting ionization due to interaction between high energy particles and gases of atmosphere, scattering of atmospheric constituents emit lights of varying energy and intensity.

Auroras visible near the North Pole are called Aurora Borealis, or Northern lights and the one visible in the South Pole is called Aurora Australis, or Southern lights.

                                                    Aurora Borealis

                                                  Aurora Australis

Different colors of Auroras

There are different colors of Auroras depending upon the energy of emitting particles-

(1)   Red = This is visible at the highest altitude where excited atomic oxygen emits at 630 nm. Due to low concentration of atoms and lower sensitivity of eyes at this altitude, this color is often visible under most extreme solar activity.

(2)   Green = Due to lower altitudes, because of increase in the number of collisions, emission occurs at 557.7 nm. The excited atomic nitrogen occurs here and plays a major role here and transforms energy by collisions to an oxygen atom, which is then radiated away at green wavelength.

(3)   Blue = At lower altitudes, volume of atomic oxygen decreases and molecular nitrogen increases. They emit wavelengths at visible emissions of light, radiating mostly in the red and blue wavelength with 428(nm) dominant.

(4)   Ultraviolet = Ultraviolet radiation has been observed with the required phenomenon. They have also been observed on Jupiter, Mars and Saturn.

                                                  Aurora on Jupiter

                                                         Aurora on Saturn                                                   

Written by :-

Sukhjit Singh

He is pursuing B.Sc in Mathematics Honours from SGTB Khalsa College, Delhi University. He often takes up multiple exciting projects and aims to develop multiple skills.

Edited by:

Shweta Mittal

Team SciComm