AIRGLOW
The short answer:
Though they appear at similar altitudes, aurora and airglow are produced by different physical processes. Nighttime airglow (or nightglow) is a type of chemiluminescence—the emission of light from chemical interactions between oxygen, nitrogen, and other molecules in the upper atmosphere. Airglow occurs all around the Earth, all the time. However, “nightglow” is much easier to spot over a dark Earth than “dayglow,” as airglow is just one billionth as bright as the Sun. [One’s camera can capture more than we can see with the naked eye, specifically, airglow colors and a more distinct Milky Way.]
Auroras, on the other hand, stem from interactions between solar energy and Earth’s magnetic field. The magnetic field funnels the energy into the upper atmosphere, where it interacts with the same atoms as airglow (mainly oxygen and nitrogen). This is why both wonders can produce similar colors. The dynamic nature of Earth’s magnetic field moves the solar energy in irregular ways, causing each aurora event to be visually unique. Source: https://earthobservatory.nasa.gov/images/147122/aurora-meet-airglow?fbclid=IwY2xjawNSHiRleHRuA2FlbQIxMABicmlkETF4R1J5ZUdyNm9VZTRNc1pSAR6XnAP7176t5LDtqb2xf_DAWwT3mc3zyw3y8DJxEWCiVsAUr5WtHF4cjPGKXw_aem_hLDjCq4NktHCQt8wrOEP-g
The long answer:
Airglow, faint luminescence of Earth’s upper atmosphere that is caused by air molecules’ and atoms’ selective absorption of solar ultraviolet and X-radiation. Most of the airglow emanates from the region about 31 to 180 miles above the surface of Earth, with the brightest area concentrated at altitudes around 60 miles. Unlike the aurora, airglow does not exhibit structures such as arcs and is emitted from the entire sky at all latitudes at all times. The nocturnal phenomenon is called nightglow. Dayglow and twilight glow are analogous terms.
Photochemical luminescence (which is also called chemiluminescence) is caused by the chemical reactions of incoming solar radiation with atoms and molecules present in the upper atmosphere. Sunlight supplies the energy needed to raise these materials to excited states, and they in turn produce emissions at particular wavelengths. Atmospheric scientists frequently observe emissions from sodium (Na), hydroxyl radical (OH), molecular oxygen (O2), and atomic oxygen (O). Emissions of sodium occur in the sodium layer some 31 to 40 miles above Earth’s surface), whereas emissions from OH, molecular oxygen, and atomic oxygen are most concentrated at altitudes of 54 miles, 60 miles, and 56–62 miles, respectively.
Radiation emitted from these molecules and atoms can be observed in the visible part of the electromagnetic spectrum. The wavelength of sodium emissions is approximately 590 nm, so they appear yellow-orange. The wavelengths of emissions from OH and molecular oxygen, however, span wide bands ranging from about 650 to 700 nm (red) and 380 to 490 nm (violet to blue), respectively. In contrast, atomic oxygen emissions occur at three distinct wavelengths located at 508 nm (green), 629 nm (orange-red), and 632 nm (red) within the electromagnetic spectrum.
Nightglow is very feeble in the visible region of the spectrum; the illumination it gives to a horizontal surface at the ground is only about the same as that from a candle at a height of 300 feet. It is possibly about 1,000 times stronger in the infrared region.
Observations from Earth’s surface and data from spacecraft and satellites indicate that much of the energy emitted during nightglow comes from recombination processes. In one such process, radiant energy is released when oxygen atoms recombine to form molecular oxygen, O2, which had originally become dissociated upon absorbing sunlight. In another process, free electrons and ions (notably ionized atomic oxygen) recombine and emit light. Source: https://www.britannica.com/science/airglowyr
Photo Airglow layers: Credit: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-Keith. Source: https://svs.gsfc.nasa.gov/12960/
The short answer:
Though they appear at similar altitudes, aurora and airglow are produced by different physical processes. Nighttime airglow (or nightglow) is a type of chemiluminescence—the emission of light from chemical interactions between oxygen, nitrogen, and other molecules in the upper atmosphere. Airglow occurs all around the Earth, all the time. However, “nightglow” is much easier to spot over a dark Earth than “dayglow,” as airglow is just one billionth as bright as the Sun. [One’s camera can capture more than we can see with the naked eye, specifically, airglow colors and a more distinct Milky Way.]
Auroras, on the other hand, stem from interactions between solar energy and Earth’s magnetic field. The magnetic field funnels the energy into the upper atmosphere, where it interacts with the same atoms as airglow (mainly oxygen and nitrogen). This is why both wonders can produce similar colors. The dynamic nature of Earth’s magnetic field moves the solar energy in irregular ways, causing each aurora event to be visually unique. Source: https://earthobservatory.nasa.gov/images/147122/aurora-meet-airglow?fbclid=IwY2xjawNSHiRleHRuA2FlbQIxMABicmlkETF4R1J5ZUdyNm9VZTRNc1pSAR6XnAP7176t5LDtqb2xf_DAWwT3mc3zyw3y8DJxEWCiVsAUr5WtHF4cjPGKXw_aem_hLDjCq4NktHCQt8wrOEP-g
The long answer:
Airglow, faint luminescence of Earth’s upper atmosphere that is caused by air molecules’ and atoms’ selective absorption of solar ultraviolet and X-radiation. Most of the airglow emanates from the region about 31 to 180 miles above the surface of Earth, with the brightest area concentrated at altitudes around 60 miles. Unlike the aurora, airglow does not exhibit structures such as arcs and is emitted from the entire sky at all latitudes at all times. The nocturnal phenomenon is called nightglow. Dayglow and twilight glow are analogous terms.
Photochemical luminescence (which is also called chemiluminescence) is caused by the chemical reactions of incoming solar radiation with atoms and molecules present in the upper atmosphere. Sunlight supplies the energy needed to raise these materials to excited states, and they in turn produce emissions at particular wavelengths. Atmospheric scientists frequently observe emissions from sodium (Na), hydroxyl radical (OH), molecular oxygen (O2), and atomic oxygen (O). Emissions of sodium occur in the sodium layer some 31 to 40 miles above Earth’s surface), whereas emissions from OH, molecular oxygen, and atomic oxygen are most concentrated at altitudes of 54 miles, 60 miles, and 56–62 miles, respectively.
Radiation emitted from these molecules and atoms can be observed in the visible part of the electromagnetic spectrum. The wavelength of sodium emissions is approximately 590 nm, so they appear yellow-orange. The wavelengths of emissions from OH and molecular oxygen, however, span wide bands ranging from about 650 to 700 nm (red) and 380 to 490 nm (violet to blue), respectively. In contrast, atomic oxygen emissions occur at three distinct wavelengths located at 508 nm (green), 629 nm (orange-red), and 632 nm (red) within the electromagnetic spectrum.
Nightglow is very feeble in the visible region of the spectrum; the illumination it gives to a horizontal surface at the ground is only about the same as that from a candle at a height of 300 feet. It is possibly about 1,000 times stronger in the infrared region.
Observations from Earth’s surface and data from spacecraft and satellites indicate that much of the energy emitted during nightglow comes from recombination processes. In one such process, radiant energy is released when oxygen atoms recombine to form molecular oxygen, O2, which had originally become dissociated upon absorbing sunlight. In another process, free electrons and ions (notably ionized atomic oxygen) recombine and emit light. Source: https://www.britannica.com/science/airglowyr
Photo Airglow layers: Credit: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-Keith. Source: https://svs.gsfc.nasa.gov/12960/
© David D. Dolton