Starship Asterisk*

HellCat wrote:A fortunate COINCIDENCE ... ?

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 ?

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.

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.)

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.>>

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?

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

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

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.

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...

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 ??

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]

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.

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?