Tuesday, February 11, 2025

Auroral "Hummingbird" over Norway

Auroral "Hummingbird" over Norway

Is this the largest hummingbird ever? Although it may look like a popular fluttering nectarivore, what is pictured is actually a beautifully detailed and colorful aurora, complete with rays reminiscent of feathers. This aurora was so bright that it was visible to the unaided eye during blue hour—just after sunset when the sky appears a darkening blue. However, the aurora only looked like a hummingbird through a sensitive camera able to pick up faint glows. As reds typically occurring higher in the Earth's atmosphere than the greens, the real 3D shape of this aurora would likely appear unfamiliar. Auroras are created when an explosion on the Sun causes high energy particles to flow into the Earth's atmosphere and excite atoms and molecules of nitrogen and oxygen. The featured image was captured about two weeks ago above Lyngseidt, Norway.

Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With approximately 366 species and 113 genera, they occur from Alaska to Tierra del Fuego, but most species are found in Central and South America.

The aurora borealis, also known as the northern lights, occurs in an upper layer of Earth’s atmosphere called the ionosphere, but they typically originate with activity on the Sun. Occasionally, during explosions called coronal mass ejections, the Sun releases charged particles that speed across the solar system. 
Auroras are produced when the Earth's magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in solar wind and magnetospheric plasma, mainly in the form of electrons and protons, precipitate them into the upper atmosphere (thermosphere/exosphere) due to Earth's magnetic field, where their energy is lost. The resulting ionization and excitation of atmospheric constituents emits light of varying color and complexity. [Wikipedia]

Solid Colored Aurora
Green is common at the upper latitudes, while red is rare. On the other hand, aurora viewed from lower latitudes tend to be red.

Element Emission Colors
Oxygen: The big player in the aurora is oxygen. Oxygen is responsible for the vivid green (wavelength of 557.7 nm) and also for a deep brownish-red (wavelength of 630.0 nm). Pure green and greenish-yellow aurorae result from the excitation of oxygen.

Nitrogen: Nitrogen emits blue (multiple wavelengths) and red light.

Other Gases: Other gases in the atmosphere become excited and emit light, although the wavelengths may be outside of the range of human vision or else too faint to see. Hydrogen and helium, for example, emit blue and purple. Although our eyes cannot see all of these colors, photographic film and digital cameras often record a broader range of hues.

Aurora Colors According to Altitude
Above 150 miles: red, oxygen
Up to 150 miles: green, oxygen
Above 60 miles: purple or violet, nitrogen
Up to 60 miles: blue, nitrogen

The Colors of the Aurora (National Park Service)


Image Credit & Copyright: Mickael Coulon
Mickael's website: 
Image Date: January 2025
Release Date: Feb. 10, 2025

#NASA #Space #Astronomy #Science #Planet #Earth #Aurora #AuroraBorealis #NorthernLights #SolarSystem #Sun #Astrophotography #Astrophotographer #MickaelCoulon #Lyngseidt #Norway #Norge #GSFC #UnitedStates #STEM #Education #APoD

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