APOD: Aurorae on Jupiter (2016 Jul 11)

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APOD: Aurorae on Jupiter (2016 Jul 11)

Post by APOD Robot » Mon Jul 11, 2016 4:10 am

Image Aurorae on Jupiter

Explanation: Jupiter has aurorae. Like Earth, the magnetic field of the gas giant funnels charged particles released from the Sun onto the poles. As these particles strike the atmosphere, electrons are temporarily knocked away from existing gas molecules. Electric force attracts these electrons back. As the electrons recombine to remake neutral molecules, auroral light is emitted. In the featured recently released composite image by the Hubble Space Telescope taken in ultraviolet light, the aurorae appear as annular sheets around the pole. Unlike Earth's aurorae, Jupiter's aurorae include several bright streaks and dots. Jupiter's Great Red Spot is visible on the lower right. Recent aurorae on Jupiter have been particularly strong -- a fortunate coincide with the arrival of NASA's Juno spacecraft at Jupiter last week. Juno was able to monitor the Solar Wind as it approached Jupiter, enabling a better understanding of aurorae in general, including on Earth.

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RocketRon

Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by RocketRon » Mon Jul 11, 2016 5:23 am

Marvellous photo, and how intriguing.

What color would the aurora be in natural light, rather than ultraviolet.
Invisible ?
Given that Jupiter itself seems to be naturally colored ?

Has anyone taken a pic of earth's aurora in UV ?

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by bystander » Mon Jul 11, 2016 5:42 am

Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Did you mean...

Post by HellCat » Mon Jul 11, 2016 7:27 am

A fortunate COINCIDENCE ... ?

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Re: Did you mean...

Post by geckzilla » Mon Jul 11, 2016 7:33 am

HellCat wrote:A fortunate COINCIDENCE ... ?
Psh, if APOD needs a new noun, it makes a new noun. :wink:
Just call me "geck" because "zilla" is like a last name.

heehaw

Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by heehaw » Mon Jul 11, 2016 8:33 am

Um...I don't follow Jovian aurorae, but I vaguely recall reading that the source of the particles that cause the aurora was Io, not the Sun. I could be wrong! (Or it could be a coincide, of course.)

Brit_in_Exile

Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Brit_in_Exile » Mon Jul 11, 2016 11:18 am

"Recent aurorae on Jupiter have been particularly strong"............are we witnessing climate change on Jupiter too ??

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Ann » Mon Jul 11, 2016 12:15 pm

RocketRon wrote:Marvellous photo, and how intriguing.

What color would the aurora be in natural light, rather than ultraviolet.
Invisible ?
Given that Jupiter itself seems to be naturally colored ?

Has anyone taken a pic of earth's aurora in UV ?
Don't know about Jupiter's auroras, but the Earth apparently has some ultraviolet ones:
https://en.wikipedia.org/wiki/Aurora#Vi ... and_colors wrote:

Red: At the highest altitudes, excited atomic oxygen emits at 630.0 nm (red); low concentration of atoms and lower sensitivity of eyes at this wavelength make this color visible only under more intense solar activity. The low amount of oxygen atoms and their gradually diminishing concentration is responsible for the faint appearance of the top parts of the "curtains". Scarlet, crimson, and carmine are the most often-seen hues of red for the auroras.

Green: At lower altitudes the more frequent collisions suppress the 630.0 nm (red) mode: rather the 557.7 nm emission (green) dominates. Fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common. The excited molecular nitrogen (atomic nitrogen being rare due to high stability of the N2 molecule) plays a role here, as it can transfer energy by collision to an oxygen atom, which then radiates it away at the green wavelength. (Red and green can also mix together to produce pink or yellow hues.) The rapid decrease of concentration of atomic oxygen below about 100 km is responsible for the abrupt-looking end of the lower edges of the curtains. Both the 557.7 and 630.0 nm wavelengths correspond to forbidden transitions of atomic oxygen, slow mechanism that is responsible for the graduality (0.7 s and 107 s respectively) of flaring and fading.

Blue: At yet lower altitudes, atomic oxygen is uncommon, and molecular nitrogen and ionized molecular nitrogen takes over in producing visible light emission; radiating at a large number of wavelengths in both red and blue parts of the spectrum, with 428 nm (blue) being dominant. Blue and purple emissions, typically at the lower edges of the "curtains", show up at the highest levels of solar activity.[22] The molecular nitrogen transitions are much faster than the atomic oxygen ones.

Ultraviolet: Ultraviolet light from auroras (within the optical window but not visible to virtually all humans) has been observed with the requisite equipment. Ultraviolet auroras have also been seen on Mars,[23] Jupiter and Saturn.

Infrared: Infrared light, in wavelengths that are within the optical window, is also part of many auroras.[23][24]
...
In addition, the aurora and associated currents produce a strong radio emission around 150 kHz known as auroral kilometric radiation AKR, discovered in 1972.[25] Ionospheric absorption makes AKR only observable from space. X-ray emissions, originating from the particles associated with auroras, have also been detected.
Of course the colors I have chosen for ultraviolet and infrared are not "true color", because the corresponding wavelengths typically don't trigger any response in the human eye.

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by neufer » Mon Jul 11, 2016 1:38 pm

heehaw wrote:
Um...I don't follow Jovian aurorae, but I vaguely recall reading that the source of the particles that cause the aurora was Io, not the Sun. I could be wrong! (Or it could be a coincide, of course.)
http://apod.nasa.gov/apod/ap001219.html
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by neufer » Mon Jul 11, 2016 1:44 pm

Brit_in_Exile wrote:
"Recent aurorae on Jupiter have been particularly strong"............are we witnessing climate change on Jupiter too ??
  • Climate change on the Sun perhaps:
https://en.wikipedia.org/wiki/Solar_cycle_24 wrote:

<<Solar Cycle 24 is the 24th solar cycle since 1755, when extensive recording of solar sunspot activity began. It is the current solar cycle, and began on January 4, 2008, but there was minimal activity until early 2010. It is on track to be the Solar Cycle with the lowest recorded sunspot activity since accurate records began in 1750. NASA directly funded and used Ken Schatten's physics-based models, which utilized a solar Dynamo model to accurately predict the low sunspot count in cycle 24. This method has used the correlation between solar magnetic field strength at solar minimum to sun spot number at solar maximum to accurately predict the peak solar flux of each of the last three solar cycles.>>
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by moconnor » Mon Jul 11, 2016 2:14 pm

With Juno now in orbit around Jupiter, there is something I don't understand.

I get that Jupiter is huge, especially in relation to the size of the Earth. But I read that we don't yet know, if Jupiter has a solid core, or not. So when Jupiter is measured today, it includes all of the gas atmosphere of Jupiter, right? But when a measurement is given for the size of the Earth (25,000 mile circumference), they don't include the gas atmosphere of Earth, do they? They're only measuring the solid core of Earth, right?

If Jupiter DOES have a solid core, is it possible that it is as small, or even smaller than the Earth's core?

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Asterhole » Mon Jul 11, 2016 2:39 pm

Jupiter would most likely have a solid core, one the size of Earth and perhaps comprised of super-compressed pure carbon, that is diamond. Or it may be a mixture of ice and rock, who knows? The outer gaseous atmosphere would only be a few hundred miles deep at most, virtually a "paper-thin" layer. As we go deeper toward the core, the gases are transformed into a semiliquid state, then becoming a metallic form of hydrogen. Sounds crazy, yes but it's a best guess by those who know more than I do.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Chris Peterson » Mon Jul 11, 2016 3:11 pm

moconnor wrote:With Juno now in orbit around Jupiter, there is something I don't understand.

I get that Jupiter is huge, especially in relation to the size of the Earth. But I read that we don't yet know, if Jupiter has a solid core, or not. So when Jupiter is measured today, it includes all of the gas atmosphere of Jupiter, right? But when a measurement is given for the size of the Earth (25,000 mile circumference), they don't include the gas atmosphere of Earth, do they? They're only measuring the solid core of Earth, right?

If Jupiter DOES have a solid core, is it possible that it is as small, or even smaller than the Earth's core?
Possible? Certainly.

That said, the Earth is a terrestrial planet and Jupiter is a gas giant. They are treated differently. A terrestrial planet is dominated by geologic processes, so we reasonably size it based on the size of its solid body. A gas giant- with or without a core- is dominated by atmospheric processes, and is mostly atmosphere, so we reasonably size it based on the top of its atmosphere.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Boomer12k » Mon Jul 11, 2016 4:41 pm

"With sugar on top...."

With such a strong magnetosphere, I am surprised it is not planet-wide...

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Chris Peterson » Mon Jul 11, 2016 4:48 pm

Boomer12k wrote:"With sugar on top...."

With such a strong magnetosphere, I am surprised it is not planet-wide...
The strength of the magnetosphere isn't the critical factor. It's the bipolar nature of it, which captures charged particles and directs them towards the magnetic poles. A stronger magnetic field actually prevents more particles from reaching lower latitudes. If you want to see auroras across an entire planet (albeit more diffuse ones), find a planet with little or no magnetic field at all.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Ann » Mon Jul 11, 2016 7:39 pm

Asterhole wrote:Jupiter would most likely have a solid core, one the size of Earth and perhaps comprised of super-compressed pure carbon, that is diamond. Or it may be a mixture of ice and rock, who knows? The outer gaseous atmosphere would only be a few hundred miles deep at most, virtually a "paper-thin" layer. As we go deeper toward the core, the gases are transformed into a semiliquid state, then becoming a metallic form of hydrogen. Sounds crazy, yes but it's a best guess by those who know more than I do.
The way I have understood it, Jupiter may not have a solid core precisely because it is so massive. After all, we don't expect the Sun to have a solid core. We don't even expect tiny little Proxima Centauri to have a solid core. We don't even expect brown dwarfs to have a solid core.

Saturn, on the other hand, is only about 30% as massive as Jupiter even though it is much the same size, and it is indeed thought to have a solid core.
Space.com wrote about Jupiter and Saturn:

Researchers modeled 50,000 what-ifs of internal structure using real data from the two planets and lab experiments that show how material behaves under extreme pressure. They found Saturn has a huge core and Jupiter may have none.

"Heavy elements are concentrated in Saturn's massive core, while those same elements are mixed throughout Jupiter, with very little or no central core at all," said Didier Saumon of the Los Alamos National Laboratory...

Saumon speculates on what might have happened with Jupiter: The king of the nine planets contains 318 times more mass than Earth (Saturn contains about 95 Earth masses). Jupiter's core would have been melted to liquid under intense pressure during formation.

"If it accreted gas very, very fast, this large amount of mass would come crashing down fast enough to induce mixing of the core," he said. The sort of heavy elements which, in the center of Saturn form a core, were instead mushed around and spread throughout Jupiter...
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Catalina » Tue Jul 12, 2016 12:39 am

Postby Brit_in_Exile » Mon Jul 11, 2016 11:18 am
"Recent aurorae on Jupiter have been particularly strong"............are we witnessing climate change on Jupiter too ??
Guess they've been driving lots of SUV's on Jupiter burning up all that fossil fuel. Guess they're causing the Great Red Spot to change, etc.

JamesTRUTHER

Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by JamesTRUTHER » Tue Jul 12, 2016 8:38 am

This photo of Jupiter dated June 30th 2016, July 11th is the SAME photo as one dated May 17th 2014.Not similar, the SAME. Nasa have just photo shopped some fake aurorae image on the top. Please watch this video to prove what I am saying
[link to video that violates the rules removed by moderator]

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by rstevenson » Tue Jul 12, 2016 12:21 pm

Ack! A TRUTHER has outed NASA! All scientists must now revise their theories!

Or... JamesTRUTHER missed the fact that NASA describes this as a composite video, and on the featured recently released composite image page NASA clearly shows that the aurorae video is just of the aurorae and that it has been added to the previously shot video of Jupiter as a way of enhancing our understanding of the location and size of the aurorae. But when have "truthers" ever cared about evidence?

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Chris Peterson » Tue Jul 12, 2016 12:30 pm

JamesTRUTHER wrote:This photo of Jupiter dated June 30th 2016, July 11th is the SAME photo as one dated May 17th 2014.Not similar, the SAME. Nasa have just photo shopped some fake aurorae image on the top. Please watch this video to prove what I am saying
[link to video that violates the rules removed by moderator]
From the NASA HubbleSite description of this image: "The full-color disk of Jupiter in this image was separately photographed at a different time by Hubble's Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of the outer planets." (Emphasis mine.)

If you look at the aurora video you'll see that the entire sequence was shot in UV, where the planet itself is largely invisible. Most of us would rather see those auroras scaled against an actual image of the planet than just an overlaid grid, hence the composite.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by DavidLeodis » Tue Jul 12, 2016 1:40 pm

In regard to the dates that the image data was acquired this should help. When clicking on the "featured recently released composite image" an image labelled 'PR Image heic1613a' can be found which is a small version of that used as the APOD. In the information when that image is clicked on it states "This image combines an image taken with Hubble Space Telescope in the optical (taken in spring 2014) and observations of its auroras in the ultraviolet, taken in 2016."

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Fred the Cat » Tue Jul 12, 2016 4:43 pm

Chris Peterson wrote:
JamesTRUTHER wrote:This photo of Jupiter dated June 30th 2016, July 11th is the SAME photo as one dated May 17th 2014.Not similar, the SAME. Nasa have just photo shopped some fake aurorae image on the top. Please watch this video to prove what I am saying
[link to video that violates the rules removed by moderator]
From the NASA HubbleSite description of this image: "The full-color disk of Jupiter in this image was separately photographed at a different time by Hubble's Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of the outer planets." (Emphasis mine.)

If you look at the aurora video you'll see that the entire sequence was shot in UV, where the planet itself is largely invisible. Most of us would rather see those auroras scaled against an actual image of the planet than just an overlaid grid, hence the composite.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by geckzilla » Tue Jul 12, 2016 6:06 pm

The truth is that Hubble is a scarce resource and while time may be devoted to observing some particularly strong auroras on Jupiter at some point, viewing Jupiter yet again in visible light is not a high priority if there is nothing substantially new to see. So they've combined data from two epochs because what we would see now and what was there two years ago is pretty much the same in visible light. Alas, even when every attempt to make this clear has been made, someone is coming up with some stupid conspiracy.
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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by Boomer12k » Tue Jul 12, 2016 10:05 pm

Chris Peterson wrote:
Boomer12k wrote:"With sugar on top...."

With such a strong magnetosphere, I am surprised it is not planet-wide...
The strength of the magnetosphere isn't the critical factor. It's the bipolar nature of it, which captures charged particles and directs them towards the magnetic poles. A stronger magnetic field actually prevents more particles from reaching lower latitudes. If you want to see auroras across an entire planet (albeit more diffuse ones), find a planet with little or no magnetic field at all.
Would that not be Mars?

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Re: APOD: Aurorae on Jupiter (2016 Jul 11)

Post by RocketRon » Wed Jul 13, 2016 5:32 am

Would that not be Mars?
That same thought occurred to me.
And presumably many others in the astronomy game.

Be interesting to see if anyone can demonstrate that Mars has any bigger/better/more/stronger/different auroae as a result.
And what would be the effect on the natives, long term ?