The aurora, known as either the northern lights (aurora borealis or southern lights (aurora australis), captivates with its dazzling light near Earth's poles. This natural phenomenon, caused by solar particles interacting with the atmosphere, showcases a spectrum of mesmerizing colors, from green to pink and blue. Delving into the science behind auroras, check out how these fascinating colors appear.
Northern lights ( aurora borealis ) illuminate the sky over the snow covered Fjord of Flakstad, on Lofoten Islands, Arctic Circle, on March 14, 2016.
Diverse Colors and Atmospheric Journey of the Northern Lights
The aurora often presents itself in the form of luminous curtains, arcs, or spirals, aligning with the Earth's magnetic field lines. This enchanting natural display exhibits a vivid spectrum of colors, ranging from the predominant green to occasional hints of pink, red, violet, and white, especially witnessed by dedicated aurora chasers during Northern Lights expeditions.
The diverse color palette of the Northern Lights is due to the intricate composition of the Earth's atmosphere, comprised of various gases distributed across different layers.
The troposphere, closest to the Earth's surface, is where clouds form due to its higher water content. As one ascends, the stratosphere absorbs UV energy from the sun through the presence of the ozone layer. Moving upward, the mesosphere and thermosphere contribute to the phenomenon, with the Northern Lights occurring at approximately 300-600 miles above the Earth's surface.
This atmospheric journey is not only marked by changing temperatures and air pressure but also by the distinct behaviors of gases at varying altitudes. The captivating colors emitted during the auroras result from the excitation of different gases in the Earth's atmosphere.
Notably, Oxygen emits the prevalent green and yellow hues when struck by solar electrons, while Nitrogen is responsible for the display of blue, red, or pink colors. Additionally, neon imparts orange tones to this celestial spectacle, creating a breathtaking visual symphony high above us.
READ ALSO: Northern Lights Extravaganza: More Aurora Displays Expected in the Next Four to Five Years
The Colors of Aurora
The primary factor influencing the colors of the aurora is the altitude at which solar particles collide with the atmosphere, exciting different gases and determining the Aurora's color. Here's how it produces each color from green to pink, and blue.
Green
As per the Canadian Space Agency, the prevalent color in auroras is green, often occurring when charged particles collide with abundant oxygen molecules at altitudes of 60 to 190 miles. Green auroras are more visible because the human eye is most sensitive to the green color spectrum.
Red
Red auroras, less frequent and associated with heightened solar activity, emerge when solar particles interact with oxygen at altitudes of 180 to 250 miles. At this higher elevation, oxygen, less concentrated, undergoes higher-frequency excitement, making red hues visible, often observed at the display's upper edges.
Blue and Purple
Blue and purple auroras are also less frequent and result from solar particles colliding with nitrogen at altitudes of 60 miles or less. These distinctive hues are often observed in the lower sections of the display, indicating specific atmospheric conditions.
Yellow and Pink
Yellow and pink auroras are also uncommon and linked to heightened solar activity. They are occasionally observed in displays, resulting from a combination of red with green or blue hues.
RELATED ARTICLE: Vibrant Green Aurora-Like Streaks of Light Illuminating the Night Sky Could Become More Common as the Sun's Activity Continues to Ramp Up
Check out more news and information on Aurora in Science Times.
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