by APOD Robot » Wed Jan 03, 2024 5:05 am
A SAR Arc from New Zealand
Explanation: What is that unusual red halo surrounding this aurora? It is a Stable Auroral Red (SAR) arc.
SAR arcs are rare and have only been acknowledged and studied since 1954. The
featured wide-angle photograph, capturing nearly an entire
SAR arc surrounding more common green and red aurora, was taken earlier this month from
Poolburn,
New Zealand, during an especially energetic
geomagnetic storm. Why
SAR arcs form remains a topic of
research, but is likely related to
Earth's protective magnetic field, a field created by
molten iron flowing deep inside the
Earth. This magnetic field usually redirects incoming charged particles from the
Sun's wind toward the Earth's poles. However, it also traps a
ring of ions closer to the equator, where they can gain energy from the
magnetosphere during high
solar activity. The energetic electrons in this
ion ring can collide with and excite oxygen higher in
Earth's ionosphere than typical
auroras, causing the oxygen to glow red.
Ongoing research has uncovered evidence that a red SAR arc
can even transform into a
purple and green
STEVE.
[url=https://apod.nasa.gov/apod/ap240103.html] [img]https://apod.nasa.gov/apod/calendar/S_240103.jpg[/img] [size=150]A SAR Arc from New Zealand[/size][/url]
[b] Explanation: [/b] What is that unusual red halo surrounding this aurora? It is a Stable Auroral Red (SAR) arc. [url=https://www.windows2universe.org/glossary/aurora_SARARC.html]SAR arc[/url]s are rare and have only been acknowledged and studied since 1954. The [url=https://www.instagram.com/p/C0e1DEXPQzR/]featured wide-angle photograph[/url], capturing nearly an entire [url=https://apod.nasa.gov/apod/ap231111.html]SAR arc[/url] surrounding more common green and red aurora, was taken earlier this month from [url=https://youtu.be/DLxQsUAXKag]Poolburn[/url], [url=https://en.wikipedia.org/wiki/New_Zealand]New Zealand[/url], during an especially energetic [url=https://en.wikipedia.org/wiki/Geomagnetic_storm]geomagnetic storm[/url]. Why [url=https://spaceweatherarchive.com/2021/11/22/3308/]SAR arcs[/url] form remains a topic of [url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JA021722]research[/url], but is likely related to [url=https://science.nasa.gov/science-research/planetary-science/earths-magnetosphere/]Earth's protective magnetic field[/url], a field created by [url=https://physics.stackexchange.com/questions/385388/even-if-molten-iron-is-ionized-spins-how-does-it-make-a-mag-field]molten iron[/url] flowing deep inside the [url=https://spaceplace.nasa.gov/menu/earth/]Earth[/url]. This magnetic field usually redirects incoming charged particles from the [url=https://apod.nasa.gov/apod/ap000318.html]Sun's wind[/url] toward the Earth's poles. However, it also traps a [url=https://en.wikipedia.org/wiki/Ring_current]ring of ions[/url] closer to the equator, where they can gain energy from the [url=https://science.nasa.gov/heliophysics/focus-areas/magnetosphere-ionosphere/]magnetosphere[/url] during high [url=https://apod.nasa.gov/apod/ap160731.html]solar activity[/url]. The energetic electrons in this [url=https://en.wikipedia.org/wiki/Ion]ion[/url] ring can collide with and excite oxygen higher in [url=https://science.nasa.gov/earth/10-things-to-know-about-the-ionosphere/]Earth's ionosphere[/url] than typical [url=https://apod.nasa.gov/apod/ap230730.html]auroras[/url], causing the oxygen to glow red. [url=https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101205]Ongoing research[/url] has uncovered evidence that a red SAR arc [url=https://allthingslearning.files.wordpress.com/2011/10/dogs_surprised.jpg]can even transform[/url] into a [url=https://apod.nasa.gov/apod/ap230927.html]purple and[/url] green [url=https://eos.org/research-spotlights/from-sar-arc-to-steve-an-atmospheric-evolution]STEVE[/url].
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