What is the chemical cause of the greens and red colors of aurora borealis (the northern lights)?
The colors come from ionized oxygen/nitrogen atoms returning to their ground state(s). You can read more about it here. Scroll down to "aurora mechanism."
http://en.wikipedia.org/wiki/Aurora_%28astronomy%29
The greens and reds in the aurora borealis are caused by different chemical reactions in Earth's atmosphere. Here are the step-by-step explanations:
1. Green light: The green color in the aurora borealis is mainly caused by the emission of light from excited oxygen atoms. The process begins when high-energy charged particles, such as electrons, from the solar wind (streams of charged particles emitted by the Sun) approach Earth.
2. Collisions with oxygen atoms: As these charged particles approach Earth, they interact with the atoms and molecules in Earth's upper atmosphere. When the charged particles collide with oxygen atoms, they transfer energy to the atoms, causing the oxygen atoms to become excited.
3. Excited oxygen atoms: The excited oxygen atoms momentarily exist in a higher energy state. These excited oxygen atoms then rapidly drop back to their original, lower-energy state and release this excess energy in the form of light.
4. Green light emission: In the case of green light, the excited oxygen atoms release the excess energy in the form of visible light with a wavelength of about 557.7 nanometers, which appears green to our eyes.
5. Red light: The red color in the aurora borealis is caused by a different process involving excited nitrogen molecules.
6. Collisions with nitrogen molecules: Similar to the green light process, the charged particles from the solar wind also collide with nitrogen molecules in the upper atmosphere.
7. Excited nitrogen molecules: When the charged particles transfer energy to the nitrogen molecules, they become excited.
8. Red light emission: The excited nitrogen molecules release the excess energy in the form of visible light with a longer wavelength, around 630 to 640 nanometers, which appears red to our eyes.
In summary, the greens and reds in the aurora borealis are caused by different reactions involving the excitation and subsequent relaxation of oxygen and nitrogen atoms/molecules in Earth's upper atmosphere, induced by charged particles from the solar wind.
The greens and reds seen in the aurora borealis, commonly known as the northern lights, are caused by different chemical reactions in the Earth's upper atmosphere. The green color is predominantly produced by excited oxygen atoms, while the red color is typically caused by excited nitrogen molecules.
To understand the chemical cause of these colors, let's break it down further:
1. Green color: The green light in the aurora borealis is mainly a result of the excitation of oxygen atoms in the Earth's upper atmosphere. High-energy electrons from the solar wind collide with oxygen atoms present at altitudes of around 100-300 kilometers. These collisions transfer energy to the oxygen atoms, exciting them to higher energy levels. When these excited oxygen atoms return to their original states, they emit photons of green light.
2. Red color: The red light of the aurora borealis is primarily due to the excitation of nitrogen molecules. Again, high-energy electrons from the solar wind interact with nitrogen molecules in the upper atmosphere, causing them to become excited. As the excited nitrogen molecules return to their normal states, they emit photons of red light.
To get this information, scientists study the emission spectra of the aurora borealis. Spectroscopy techniques allow them to analyze the various wavelengths of light emitted by the excited atoms and molecules during the auroral displays.
In summary, the chemical cause of the green and red colors of the aurora borealis is the excitation and subsequent emission of light by oxygen atoms (green) and nitrogen molecules (red) in the Earth's upper atmosphere, triggered by high-energy particles from the Sun.