APOD: The Dancing Auroras of Saturn (2021 Jun 27)

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APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by APOD Robot » Sun Jun 27, 2021 4:05 am

Image The Dancing Auroras of Saturn

Explanation: What drives auroras on Saturn? To help find out, scientists have sorted through hundreds of infrared images of Saturn taken by the Cassini spacecraft for other purposes, trying to find enough aurora images to correlate changes and make movies. Once made, some movies clearly show that Saturnian auroras can change not only with the angle of the Sun, but also as the planet rotates. Furthermore, some auroral changes appear related to waves in Saturn's magnetosphere likely caused by Saturn's moons. Pictured here, a false-colored image taken in 2007 shows Saturn in three bands of infrared light. The rings reflect relatively blue sunlight, while the planet itself glows in comparatively low energy red. A band of southern aurora in visible in green. In has recently been found that auroras heat Saturn's upper atmosphere. Understanding Saturn's auroras is a path toward a better understanding of Earth's auroras.

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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by emc » Sun Jun 27, 2021 11:33 am

https://youtu.be/ujmGiBl36f8
Click to play embedded YouTube video.

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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by neufer » Sun Jun 27, 2021 1:06 pm

APOD Robot wrote:
Sun Jun 27, 2021 4:05 am

Explanation: What drives auroras on Saturn?.
https://en.wikipedia.org/wiki/Oldsmobile_Aurora wrote:
<<The Oldsmobile Aurora was a flagship sedan made by Oldsmobile from 1994 to 2003. It was a luxury sports sedan produced in two generations which, along with the two-door Buick Riviera, originated the Cadillac-derived G platform. Aurora was the official pace car of the 1997 and 2000 Indianapolis 500. At the beginning of the race in 1997, the pace car was driven by three-time Indy 500 winner Johnny Rutherford. At the beginning of the 2000 race, the pace car was driven by actor Anthony Edwards. These cars marked the ninth and tenth time an Oldsmobile had paced the Indianapolis 500 race.>>
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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by johnnydeep » Sun Jun 27, 2021 3:31 pm

emc wrote:
Sun Jun 27, 2021 11:33 am
[youtube]https://youtu.be/ujmGiBl36f8[/youtube]
FYI, the youtube link parser only seems to understand the www.youtube.com and youtube.com domains, as in https://www.youtube.com/watch?v=ujmGiBl36f8 -

Click to play embedded YouTube video.
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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by orin stepanek » Sun Jun 27, 2021 4:13 pm

neonsaturnaurora_cassini_2560.jpg
!


Reminds me of a party lantern! 8-)
It is beautiful

BUCOEePIcAAht9h.jpg
Kitty even lazier then Magic! :lol2:
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Smile today; tomorrow's another day!

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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by VictorBorun » Sun Jun 27, 2021 5:18 pm

The legend specifies color mapping, and the colors are sorted in the natural order:
5 microns as red (Saturn's thermal emission from under the clouds)
3 and 4 microns as green (some hydrogen ions in aurora)
2 to 3 microns as blue (sunshine in near infrared)

Why then the picture looks spooky paranormal?
There is no greenish hues like yellow or cyan.
The only hue sectors filled are red-blue: the purple and the magenta.

To make the pic less ghostly we can re-arrange like this:
5 microns as red (Saturn's thermal emission from under the clouds)
2 to 3 microns as green (sunshine in near infrared)
3 and 4 microns as blue (some hydrogen ions in aurora)

Then aurora's hydrogen ions fluorescent out of the natural order, but we get the advantage to see as the red thermal glow from under the clouds merges naturally with the green of sunshine, making orange to yellow to lime:

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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by Chris Peterson » Sun Jun 27, 2021 5:33 pm

VictorBorun wrote:
Sun Jun 27, 2021 5:18 pm
The legend specifies color mapping, and the colors are sorted in the natural order:
5 microns as red (Saturn's thermal emission from under the clouds)
3 and 4 microns as green (some hydrogen ions in aurora)
2 to 3 microns as blue (sunshine in near infrared)

Why then the picture looks spooky paranormal?
There is no greenish hues like yellow or cyan.
The only hue sectors filled are red-blue: the purple and the magenta.

To make the pic less ghostly we can re-arrange like this:
5 microns as red (Saturn's thermal emission from under the clouds)
2 to 3 microns as green (sunshine in near infrared)
3 and 4 microns as blue (some hydrogen ions in aurora)

Then aurora's hydrogen ions fluorescent out of the natural order, but we get the advantage to see as the red thermal glow from under the clouds merges naturally with the green of sunshine, making orange to yellow to lime:
If you're interested in actually analyzing the image based on wavelengths, about the only way to do it is to separate the three color planes completely, and present them as individual images, either in grayscale or a pseudocolor palette.
Chris

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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by MarkBour » Mon Jun 28, 2021 4:33 pm

Since the wavelengths are longer than one micrometer, I guess that if we had a seat on Cassini, human eyes would not have been able to see this aurora.
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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by neufer » Mon Jun 28, 2021 5:08 pm

MarkBour wrote:
Mon Jun 28, 2021 4:33 pm

Since the wavelengths are longer than one micrometer, I guess that if we had a seat on Cassini, human eyes would not have been able to see this aurora.
This aurora is entirely in daylight.

Human eyes do not see daylight aurora.
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Re: APOD: The Dancing Auroras of Saturn (2021 Jun 27)

Post by VictorBorun » Mon Jun 28, 2021 6:17 pm

Chris Peterson wrote:
Sun Jun 27, 2021 5:33 pm
If you're interested in actually analyzing the image based on wavelengths, about the only way to do it is to separate the three color planes completely, and present them as individual images, either in grayscale or a pseudocolor palette.
Or we can just dim and downplay the other channels.
Here I made the sunshine yellow (it is still in the right wavelength order in relation to red of the Suturn's thermal glow) and dimmed both the sunshine and the Suturn's thermal glow: