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SAR Arc and Airglow Panorama from Arizona
SAR Arc and Airglow Panorama (Arizona, Oct 7, 2024).jpg
This is a 360° panorama of the night sky in southeastern Arizona on October 7, 2024, with a major Kp7-level aurora storm going on.
SAR Arc —
From this latitude of 32° N the main sign of the aurora is the red arc across the north, a Stable Auroral Red (SAR) arc, a phenomenon related to auroras and present during an active display. But SAR arcs are not auroras per se, in that they are not created by energetic particles raining down from the distant parts of the Earth's magnetosphere, but by hot gases flowing horizontally and generated by "ring currents" in the inner magnetosphere.
From my location the SAR arc appeared low across the north. From sites farther north in the mid-U.S. this night, the SAR arc appeared higher, perhaps overhead or, from Canada, to the south. SAR arcs are always equatorward of the main aurora band, to the south of an aurora in the northern hemisphere. They can be at 400 km or higher altitudes, so very high and effectively in space. SARs may be related to STEVE arcs, as a SAR can evolved into a brighter and mauve STEVE arc. But that did not happen this night — I shot a time-lapse hoping to capture such a transition.
However, aout an hour later some "normal" red auroral curtains did appear low on the horizon, unusual for such a low latitude but possible during a Kp7 or higher storm.
Airglow —
The panorama also shows green sky around the horizon from airglow, another phenomenon not related to auroras, but caused by oxygen atoms (in this case) fluorescing at night as they release energy absorbed from the Sun by day, typically from an altitude of about 100 km.
Gegenschein —
Just visible in the upper right corner to the southeast is a faint glow from "Gegenschein," from sunlight reflecting off dust particles in the outer solar system, so not an atmospheric phenomenon like airglow and auroras.
Location and Time —
The location was the Quailway Cottage between Portal, Arizona and Rodeo, New Mexico, about 50 km north of the Me
SAR Arc —
From this latitude of 32° N the main sign of the aurora is the red arc across the north, a Stable Auroral Red (SAR) arc, a phenomenon related to auroras and present during an active display. But SAR arcs are not auroras per se, in that they are not created by energetic particles raining down from the distant parts of the Earth's magnetosphere, but by hot gases flowing horizontally and generated by "ring currents" in the inner magnetosphere.
From my location the SAR arc appeared low across the north. From sites farther north in the mid-U.S. this night, the SAR arc appeared higher, perhaps overhead or, from Canada, to the south. SAR arcs are always equatorward of the main aurora band, to the south of an aurora in the northern hemisphere. They can be at 400 km or higher altitudes, so very high and effectively in space. SARs may be related to STEVE arcs, as a SAR can evolved into a brighter and mauve STEVE arc. But that did not happen this night — I shot a time-lapse hoping to capture such a transition.
However, aout an hour later some "normal" red auroral curtains did appear low on the horizon, unusual for such a low latitude but possible during a Kp7 or higher storm.
Airglow —
The panorama also shows green sky around the horizon from airglow, another phenomenon not related to auroras, but caused by oxygen atoms (in this case) fluorescing at night as they release energy absorbed from the Sun by day, typically from an altitude of about 100 km.
Gegenschein —
Just visible in the upper right corner to the southeast is a faint glow from "Gegenschein," from sunlight reflecting off dust particles in the outer solar system, so not an atmospheric phenomenon like airglow and auroras.
Location and Time —
The location was the Quailway Cottage between Portal, Arizona and Rodeo, New Mexico, about 50 km north of the Me
- Copyright
- © Alan Dyer/AmazingSky.com
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- 29596x6249 / 82.4MB
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