How Do Auroras Happen?
Auroras are luminous atmospheric phenomena in the night sky that occur most frequently in the high latitudes of both hemispheres. They are categorized specifically according to their location. Auroras in the Northern Hemisphere are called the Northern Lights (Aurora Borealis), and in the Southern Hemisphere, auroras are called the Southern Lights (Aurora Australis). The stunning phenomenon has captivated humanity for centuries, leaving us in awe of the dancing curtains of vibrant colors that grace the night sky. But how did these magical lights come to be?Â
Auroras are caused by the sun, but they are not just the sunlight. In addition to light, the sun also sends out an electrically charged stream of electrons and protons, called the solar wind. This stream of particles travels from the sun towards the Earth at high speed. As the solar wind travels through space, it eventually reaches our planet. The Earth possesses its own protective shield in the form of a magnetic field. This magnetic field is generated by the movement of molten iron in the Earth's outer core. The field lines emerge from the North Pole, curve around the Earth, and re-enter at the South Pole, creating a magnetic envelope around our planet.Â
When the charged particles from the solar wind approach the Earth, they encounter our magnetic field. The interaction between the magnetic field lines and the charged particles leads to a fascinating phenomenon called magnetic reconnection. This interaction takes place in a region of space around the Earth called the magnetosphere. The magnetosphere acts as a shield, deflecting most of the charged particles away from the planet. However, some of the charged particles manage to enter the Earth's atmosphere near the North and South Poles. As they collide with the atoms and molecules in the atmosphere, particularly oxygen and nitrogen, they transfer energy to them. This energy transfer excites the atoms and molecules, causing them to move to higher energy states.
After being excited, the atoms and molecules in the atmosphere gradually return to their normal energy states, releasing the excess energy in the form of light. The specific colors of light emitted depend on the type of atom or molecule involved. Oxygen molecules typically emit green and red light, while nitrogen molecules emit blue and purple light. The released light forms the breathtaking colors that we associate with auroras. The excited atoms and molecules simultaneously releasing their energy create a luminous curtain of light that dances across the sky. The colors and patterns of the auroras can vary, influenced by factors such as the altitude at which the collisions occur and the specific energy levels involved. The light of auroras is not strong enough too, they are generally only visible at night.
