What exactly is Aurora?
An Aurora is a natural light display in the sky. It is caused by the collision of charged particles coming from space with the collision of atmospheric atoms in the high-altitude atmosphere. It is commonly seen in the high latitude areas like the Arctic and Antarctic. Aurora is also called Polar Lights, Northern Lights, Aurora Borealis, Aurora Polaris, or Southern lights, Aurora Australis.
Who coined the name Aurora?
In 1619, an Italian astronomer Galileo Galilei had coined the name “aurora borealis” after the Roman goddess of dawn, Aurora, and the Greek god of the north wind, Boreas.
Why are auroras of various hues and shapes?
• The color of the aurora is determined by whether the gas is stimulated by the electrons (oxygen or nitrogen) and how excited it gets. The color is determined by how rapidly the electrons are traveling or how much energy they have when they collide.
• Low energy electrons create red light, whereas high energy electrons cause green light (the most popular color of the aurora).
• Purples, pinks, and whites can be created by mixing these hues. Ultraviolet light is emitted by oxygen and nitrogen, and which may be detected by sophisticated satellite cameras.
WHERE DO THE NORTHERN LIGHTS COME FROM?
- The aurora is caused by electrically charged particles from the sun colliding with one other when they reach the earth’s atmosphere.
- Auroral displays come in a variety of colors, but the most common are pale green and pink. There have been reports of red, yellow, green, blue, and violet hues.
- Aurora lights come in a variety of shapes and sizes, ranging from the display of dynamic patterns, patches, or scattered clouds of brilliant lights that appear as rays, arcs, spirals, shooting beams, rippling curtains, streamers, or dynamic flickers that cast an eerie glow covering the entire sky.
WHAT ARE THE REASONS FOR THE NORTHERN LIGHTS?
- The Northern Lights appear due to the collisions between gaseous particles in the earth’s atmosphere and the charged particles emitted from the sun’s atmosphere.
- The type of gas particles colliding determines the color variations. Oxygen molecules positioned around 60 miles above the earth form the most frequent auroral hue, a mild yellowish-green.
- At altitudes of up to 200 miles, high-altitude oxygen produces rare, all-red auroras.
- Nitrogen causes the aurora to be blue or purplish-red.
Ozone and the Northern Lights
- Solar Wind is created when the sun releases millions of electrons from its upper atmosphere, at any given time.
- These particles collide with the ozone layer on earth and get trapped in the magnetosphere i.e., the earth’s magnetic field.
- Electron-plasma wave entangling can allow trapped electrons to escape and reach the earth’s upper atmosphere (thermosphere).
- This is known as precipitation, and it is what causes the aurorae to appear. However, this causes local ozone layer depletion in the lower layer i.e., the mesosphere. It would have an effect on the world’s climate, vegetation, and environment at various levels.
- Electron precipitation had been researched thoroughly by scientists to establish a connection to the aurorae. But no one has been able to explain in detail how it causes mesospheric ozone depletion.