APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Comments and questions about the APOD on the main view screen.
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APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by APOD Robot » Tue Dec 06, 2016 5:09 am

Image Aurora over Jupiter's South Pole from Juno

Explanation: Why is there a glowing oval over Jupiter's South Pole? Aurora. Near the closest part of its first pass near Jupiter in August, NASA's robotic spacecraft Juno captured this dramatic infrared image of a bright auroral ring. Auroras are caused by high energy particles from the Sun interacting with a planet's magnetic field, and ovals around magnetic poles are common. Data from Juno are giving preliminary indications that Jupiter's magnetic field and aurorae are unexpectedly powerful and complex. Unfortunately, a computer glitch caused Juno to go into safe mode during its last pass near the Jovian giant in September. That glitch has now been resolved, making Juno ready for its next pass over Jupiter's cloud tops this coming Sunday.

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Boomer12k » Tue Dec 06, 2016 6:10 am

I hope it can get another great shot... awesome...

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by heehaw » Tue Dec 06, 2016 12:55 pm

Many decades ago, sounding rocket observations of Jupiter showed ultraviolet light, to the surprise of the observers. Subsequent flights showed different brightnesses ... it seemed: the observers decided their error bars on the observations must be too small. They thus missed discovering the polar auroras. Oh well.

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by ta152h0 » Tue Dec 06, 2016 2:02 pm

need to not imgine Dante's Inerno anymore. There it is in full view
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Wadsworth » Tue Dec 06, 2016 2:25 pm

Why such poor resolution?

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by neufer » Tue Dec 06, 2016 2:45 pm

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Asterhole » Tue Dec 06, 2016 3:28 pm

Everything we see that happens on Jupiter is on a scale many hundredfold of what we'd have here on our dinky little planet. It's doubtful Mankind will be able to visit this place other than by remote observations.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Chris Peterson » Tue Dec 06, 2016 4:10 pm

Wadsworth wrote:Why such poor resolution?
"Poor" is a subjective term. We're all so used to astronomical observations made with very high pixel count cameras that we expect it now. But not all instruments produce such high density data. L and M band IR sensor arrays tend to be much smaller- 432x128 in this case.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Leon1949Green » Tue Dec 06, 2016 4:13 pm

Is there a real-color image available?

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Chris Peterson » Tue Dec 06, 2016 4:19 pm

Leon1949Green wrote:Is there a real-color image available?
I don't think they're generally bright enough to see with the visible light imagers that are available. All the images I've seen are UV or IR, sometimes superimposed on visible light images of Jupiter. They might show up in visible light against the night side of the planet, but I don't recall seeing such an image.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by neufer » Tue Dec 06, 2016 7:24 pm

Chris Peterson wrote:
Wadsworth wrote:
Why such poor resolution?
"Poor" is a subjective term. We're all so used to astronomical observations made with very high pixel count cameras that we expect it now. But not all instruments produce such high density data. L and M band IR sensor arrays tend to be much smaller- 432x128 in this case.
Angular resolution of the human eye: ~ 300 μrad
Angular resolution of JIRAM: ~ 240 μrad
https://en.wikipedia.org/wiki/Jovian_Infrared_Auroral_Mapper wrote: <<Jovian Infrared Auroral Mapper (JIRAM) is an instrument on the Juno spacecraft in orbit of the planet Jupiter. It is an image spectrometer and was contributed by Italy. Similar instruments are on ESA Rosetta, Venus Express, and Cassini-Huygens missions. The primary goal of JIRAM is to probe the upper layers of Jupiter's atmosphere down to pressures of 5–7 bars at infrared wavelengths in the 2–5 μm interval using an imager and a spectrometer. Jupiter's "hot spots" and auroral regions are targeted for study.

It is hoped H3+ ions, ammonia, and phosphine can be mapped. The ion of Hydrogen H3+ is rare on Earth, but is one of the most common ions in the universe and known as protonated molecular hydrogen or the trihydrogen cation.>>
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Chris Peterson » Tue Dec 06, 2016 7:30 pm

neufer wrote:
Chris Peterson wrote:
Wadsworth wrote: Why such poor resolution?
"Poor" is a subjective term. We're all so used to astronomical observations made with very high pixel count cameras that we expect it now. But not all instruments produce such high density data. L and M band IR sensor arrays tend to be much smaller- 432x128 in this case.
Angular resolution of the human eye: ~ 300 μrad
Angular resolution of JIRAM: ~ 240 μrad
Of course, we tend to perceive resolution in terms of smoothness, not actual scale of detail. So a pixelated image appears to have "poor" resolution even if it actually has a true spatial resolution greater than our eyes.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by neufer » Tue Dec 06, 2016 8:05 pm

Chris Peterson wrote:
neufer wrote:
Angular resolution of the human eye: ~ 300 μrad
Angular resolution of JIRAM: ~ 240 μrad
Of course, we tend to perceive resolution in terms of smoothness, not actual scale of detail. So a pixelated image appears to have "poor" resolution even if it actually has a true spatial resolution greater than our eyes.
  • One needs to move one's chair back far enough that the pixelation is no longer resolvable.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Chris Peterson » Tue Dec 06, 2016 8:14 pm

neufer wrote:
Chris Peterson wrote:
neufer wrote:
Angular resolution of the human eye: ~ 300 μrad
Angular resolution of JIRAM: ~ 240 μrad
Of course, we tend to perceive resolution in terms of smoothness, not actual scale of detail. So a pixelated image appears to have "poor" resolution even if it actually has a true spatial resolution greater than our eyes.
  • One needs to move one's chair back far enough that the pixelation is no longer resolvable.
Yup. Or blur it with a filter having a kernel size about that of the superpixel size. Or just reduce the image size.
Aurora2_Juno_1041-copy-2.jpg
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by MarkBour » Tue Dec 06, 2016 10:06 pm

I'd appreciate it if someone could help me better understand what I'm seeing in this gorgeous image. (It looks to the human eye almost like a fire, though I doubt it is even warm by Earth standards.)

First, I suppose the pixellation itself is a major artifact, perhaps you professional imagers would refer to it that way, whereas one would assume the reality of the scene being captured would be smoothed. But I need no more explanation about that. Second, though, I think I see some other artifacts. There are a few bright dots that, because of their perfect vertical alignment I assume to be artifacts. Correct? There are also some dark (black?) dots, which are more closely-spaced and thus greater in number along another vertical line. Artifacts, I assume. What would cause either of these?
Capture.JPG

Third, there is a very interesting shape at the lower left. It seems like it would not be an artifact. Shown in the excerpt here. Is that something interesting? (Does not appear to be Clark's monolith.)





More generally, I see the bright yellow shading in a ring, and I'm thinking that is the aurora itself. If that's the case, then it looks like there is a ridge of cloud around the aurora, with the aurora kind of painting itself along its inner wall. But would an IR image show us this? Is that indeed a doughnut-shaped cloud?
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by neufer » Wed Dec 07, 2016 12:59 pm

MarkBour wrote:
There is a very interesting shape at the lower left. It seems like it would not be an artifact. Shown in the excerpt here. Is that something interesting? (Does not appear to be Clark's monolith.)
Anything that shape this time of year over a pole is probably Santa's sleigh.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Ann » Wed Dec 07, 2016 1:14 pm

neufer wrote:
MarkBour wrote:
There is a very interesting shape at the lower left. It seems like it would not be an artifact. Shown in the excerpt here. Is that something interesting? (Does not appear to be Clark's monolith.)
Anything that shape this time of year over a pole is probably Santa's sleigh.
Ho-ho-ho!

Image

Are there any good children here at Jupiter? Io? Europa? Ganymede? Callisto? Santa-colored Amalthea?

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by DavidLeodis » Wed Dec 07, 2016 9:36 pm

I've learnt a new word in the information brought up through the "this dramatic infrared image" link, namely "perijove". As perigee is the nearest between two objects I assume perijove is the nearest to Jupiter (here as 'perijove pass' of Juno). By jove it will, using the old expression of exclamation :wink:.

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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by neufer » Wed Dec 07, 2016 10:33 pm

Ann wrote:
neufer wrote:
MarkBour wrote:
There is a very interesting shape at the lower left. It seems like it would not be an artifact. Shown in the excerpt here. Is that something interesting? (Does not appear to be Clark's monolith.)
Anything that shape this time of year over a pole is probably Santa's sleigh.
  • Ho-ho-ho!
  • Oh, yeah,....and that Jovial.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by Chris Peterson » Wed Dec 07, 2016 10:36 pm

DavidLeodis wrote:I've learnt a new word in the information brought up through the "this dramatic infrared image" link, namely "perijove". As perigee is the nearest between two objects I assume perijove is the nearest to Jupiter (here as 'perijove pass' of Juno). By jove it will, using the old expression of exclamation :wink:.
The "gee" in "perigee" is a reference to the Earth (as in GEology). It is the point in a body's orbit where it is closest to Earth. Perihelion is the point that an orbiting body is closest to the Sun. Perijove is the point that an orbiting body is closest to Jupiter. The general term for the extremes of an orbit is apsis. A body is closest to what it orbits at its periapsis, and farthest at its apapsis.
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Re: APOD: Aurora over Jupiter's South Pole... (2016 Dec 06)

Post by DavidLeodis » Fri Dec 09, 2016 2:07 pm

Chris Peterson wrote:
DavidLeodis wrote:I've learnt a new word in the information brought up through the "this dramatic infrared image" link, namely "perijove". As perigee is the nearest between two objects I assume perijove is the nearest to Jupiter (here as 'perijove pass' of Juno). By jove it will, using the old expression of exclamation :wink:.
The "gee" in "perigee" is a reference to the Earth (as in GEology). It is the point in a body's orbit where it is closest to Earth. Perihelion is the point that an orbiting body is closest to the Sun. Perijove is the point that an orbiting body is closest to Jupiter. The general term for the extremes of an orbit is apsis. A body is closest to what it orbits at its periapsis, and farthest at its apapsis.
Thanks Chris :).

I had not realised (or had forgotten :oops: ) that the 'gee' bit refers to the Earth.

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Apsis makes the tooth grow looser

Post by neufer » Fri Dec 09, 2016 4:21 pm

Chris Peterson wrote:
The "gee" in "perigee" is a reference to the Earth (as in GEology). It is the point in a body's orbit where it is closest to Earth. The general term for the extremes of an orbit is apsis. A body is closest to what it orbits at its periapsis, and farthest at its apapsis.
https://en.wikipedia.org/wiki/Geology wrote:
<<Geology (from the Ancient Greek γῆ, gē, i.e. "earth" and -λoγία, -logia, i.e. "study of, discourse") can also refer generally to the study of the solid features of any celestial body (such as the geology of the Moon or Mars).>>
https://en.wikipedia.org/wiki/Apsis wrote:
<<An apsis (Greek: ἁψίς; plural apsides) is an extreme point in an object's orbit. The word is cognate with apse (from Latin absis: "arch, vault" from Greek ἀψίς apsis "arch"; sometimes written apsis). For elliptic orbits about a larger body, there are two apsides, named with the prefixes peri- (from περί (peri), meaning "near") and ap-, or apo- (from ἀπ(ό) (ap(ó)), meaning "away from") added to a reference to the thing being orbited. For any orbits around a center of mass, the terms periapsis and apoapsis (or apapsis) are equivalent alternatives.>>
https://en.wikipedia.org/wiki/Apology_(Plato) wrote:
<<The Apology of Socrates (Greek: ἀπολογία; "speaking in defense"), by Plato, is the Socratic dialogue that presents the speech of legal self-defence, which Socrates presented at his trial for impiety and corruption, in 399 BC. Specifically it is a defence against the charges of “corrupting the young” and “not believing in the gods in whom the city believes, but in other daimonia that are novel” to Athens.>>
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