Explanation: Jupiter is stranger than we knew. NASA's Juno spacecraft has now completed its sixth swoop past Jupiter as it moves around its highly elliptical orbit. Pictured, Jupiter is seen from below where, surprisingly, the horizontal bands that cover most of the planet disappear into swirls and complex patterns. A line of white oval clouds is visible nearer to the equator. Recent results from Juno show that Jupiter's weather phenomena can extend deep below its cloud tops, and that Jupiter's magnetic field varies greatly with location. Juno is scheduled to orbit Jupiter 37 times with each orbit taking about six weeks.
APOD Robot wrote:... scheduled to orbit Jupiter 37 times with each orbit taking about six weeks.
37 orbits is not correct - that count applies to the original 14-day science orbits.
Given the mission is scheduled to end in July 2018, and it's on a 53-day orbit, that's only about 8 orbits from the last perijove (5/19).
Edit: Considering a polar insertion date of July 5, 2016, Juno's total number of science orbits ≈ 14
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Mon May 29, 2017 7:12 am
by ygmarchi
I think the white ovals band is about 45° of latitude not near the equator.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Mon May 29, 2017 9:29 am
by evo
have you noticed the man,s head,white eye and arm and fingers on the meddle left
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Mon May 29, 2017 2:19 pm
by Chris Peterson
ygmarchi wrote:I think the white ovals band is about 45° of latitude not near the equator.
Or even higher. But the caption says nearer the equator, not near, which seems like an accurate way of putting it.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Mon May 29, 2017 3:29 pm
by douglas
" .. Data gathered during the first few passes has revealed that ammonia abundances vary quite a bit from place to place — a discovery that surprised the mission team.
"Most scientists have felt that, as soon as you go down a little bit into Jupiter, everything would be well-mixed, and we're finding that that's just not true at all," Bolton said. "There's structure down deep, but it doesn't seem to match the zones and belts."
" .. Juno's measurements during the first few close passes also show that Jupiter's magnetic field is nearly two times stronger than scientists had predicted. And the probe's gravity data suggest that "there's a lot of strange, deep motions that possibly are going on inside of Jupiter,"
" .. the particles associated with Jupiter's auroras seem to be different than the ones responsible for Earth's most stunning light shows, study team members said.
"We can see that it doesn't work exactly like we expected, or as the Earth does," Bolton said. "We haven’t been able to see particles necessarily going up and down in both directions like we would've expected to cause the aurora. So there's definitely some strange phenomena that we still need to comb through and understand better."
" .. There seems to be a fuzzy core, and it may be much larger than anybody had anticipated," Bolton said Thursday (May 25) during a NASA press conference announcing the first detailed science results from Juno's mission.
This core may even be partially dissolved, Bolton said, adding that Juno's initial observations are also consistent with "some deep motions or zonal winds" occurring far beneath the enormous planet's cloud tops."
Does Jupiter's core mix the atmosphere, like a paddle-stirrer?
" .. The Juno Microwave Radiometer, which probed hundreds of kilometers beneath the surface, found a remarkable level of organization — including a strange band of ammonia sitting right above the equator that extends deep into the planet."
" .. In fact, this band of ammonia seems to have dynamics somewhat reminiscent of an atmospheric circulation pattern on Earth known as a Hadley Cell — even though that pattern requires a surface like Earth’s land or oceans to work."
" .. results show that Jupiter’s magnetic field might actually be generated higher up, in the shallower layer of molecular hydrogen (which is strange, since molecular hydrogen is a neutral compound).
“That’s very significant,” John Connerney .. "
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Mon May 29, 2017 3:45 pm
by douglas
“ .. Up until last week, our models of Jupiter’s auroras had the electrons going in the wrong direction.” On Earth, electrons in the planet’s magnetic field get excited by solar wind and then funneled toward the poles, where they bang into other atoms and molecules and emit light. On Jupiter, Juno’s instruments have found that electrons actually get excited when pulled out of polar regions."
“ .. If Jupiter is just a big, rotating gas ball, it should not have any odd harmonics in its gravity field,” says Connerney. But Jupiter’s gravity isn’t uniform, which might suggest deep convection—density differentials deep inside Jupiter might drive gravity fluctuations the same way atmospheric pressure differentials drive weather on Earth. Juno’s readings of the planet’s magnetic field were also much more geographically variable than scientists expected.
.. Connerney ventures that the fluctuations may all be connected, with the deep convection expressed in the gravity field also driving the uneven magnetic field strength."
<<A Taylor column is a fluid dynamics phenomenon that occurs as a result of the Coriolis effect. It was named after Geoffrey Ingram Taylor. Rotating fluids that are perturbed by a solid body tend to form columns parallel to the axis of rotation called Taylor columns. Taylor columns were first observed by William Thomson, Lord Kelvin, in 1868. Taylor columns were featured in lecture demonstrations by Kelvin in 1881 and by John Perry in 1890.
An object moving parallel to the axis of rotation in a rotating fluid experience more drag force than what it would experience in a non rotating fluid. For example, a strongly buoyant ball (such as a pingpong ball) will rise to the surface slower than it would in a non rotating fluid. This is because fluid in the path of the ball that is pushed out of the way tends to circulate back to the point it is shifted away from, due to the Coriolis effect. The faster the rotation rate, the smaller the radius of the inertial circle traveled by the fluid.
A unit of fluid (represented by the black dot) is pushed back to the point it is shifted from.
In a non-rotating fluid the fluid parts above the rising ball and closes in underneath it, offering relatively little resistance to the ball. In a rotating fluid, the ball needs to push up a whole column of fluid above it, and it needs to drag a whole column of fluid along beneath it in order to rise to the surface.>>
Would love to see an animation of the vortices evolving (and maybe devolving) at these eternally dim poles. Though perhaps not possible with the planned orbital pattern of Juno. Whilst there are a lot of other tasks keeping Juno busy, these first polar images are quite special, though perhaps not entirely unexpected. I think a large hexagonal vortex (like on Saturn's more tilted poles) would have been more surprising.
Do you know if the 2 (?) papers they've published have given all their gravity data? You'd think with as high-energy a system Jupiter's interior is it would have been fully presented by now? Or that those who've read them would mention their details?
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Tue May 30, 2017 2:01 am
by bystander
douglas wrote:
Do you know if the 2 (?) papers they've published have given all their gravity data? You'd think with as high-energy a system Jupiter's interior is it would have been fully presented by now? Or that those who've read them would mention their details?
Not sure, I don't think either of the papers at Science are about gravity, but there are 44 papers at Geophysical Research Letters, five of which are in Gravitational and Magnetic Field Measurements.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Tue May 30, 2017 6:45 pm
by douglas
Can you imagine the problems these measures must be giving their models??
" .. results show that Jupiter’s magnetic field might actually be generated higher up, in the shallower layer of molecular hydrogen (which is strange, since molecular hydrogen is a neutral compound).
douglas wrote:Can you imagine the problems these measures must be giving their models??
No problems at all! This is exactly the sort of stuff that's needed to refine the models. Up to now, so much could only be tested by comparing upper atmosphere clouds between the simulations and reality. Now there are so many more physical parameters to work with.
That's the fundamental reason that missions like this are funded.
Nitpicker wrote:
Would love to see an animation of the vortices evolving (and maybe devolving) at these eternally dim poles. Though perhaps not possible with the planned orbital pattern of Juno. Whilst there are a lot of other tasks keeping Juno busy, these first polar images are quite special, though perhaps not entirely unexpected.
I think a large hexagonal vortex (like on Saturn's more tilted poles) would have been more surprising.
Saturn has:
1) a much thicker atmosphere,
2) stronger jet streams,
3) more internal heat and
4) a weaker magnetic field
than Jupiter.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Tue May 30, 2017 10:13 pm
by Nitpicker
Indeed all the differences between Jupiter and Saturn are why I wasn't expecting hexagon patterns, which require fairly specific conditions.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 12:23 am
by douglas
Chris Peterson wrote:
douglas wrote:Can you imagine the problems these measures must be giving their models??
No problems at all! This is exactly the sort of stuff that's needed to refine the models. Up to now, so much could only be tested by comparing upper atmosphere clouds between the simulations and reality. Now there are so many more physical parameters to work with.
That's the fundamental reason that missions like this are funded.
" .. results show that Jupiter’s magnetic field might actually be generated higher up, in the shallower layer of molecular hydrogen (which is strange, since molecular hydrogen is a neutral compound)."
I should think that, yes, they know neutral molecular hydrogen is not capable of generating a magnetic field, and would also have some sense as to how neutral molecular hydrogen would mediate a field generated in the lower layers and it is not comporting with what they're measuring.
They've already spoken of having to totally re-think their gas giant model for Jupiter and have emphasized real-world measures are far preferred to remote modeling, so they're a bit surprised the models are so wrong.
At least they haven't fallen upon an IMBH as explanation! /sarc
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 12:43 am
by Chris Peterson
douglas wrote:
Chris Peterson wrote:
douglas wrote:Can you imagine the problems these measures must be giving their models??
No problems at all! This is exactly the sort of stuff that's needed to refine the models. Up to now, so much could only be tested by comparing upper atmosphere clouds between the simulations and reality. Now there are so many more physical parameters to work with.
That's the fundamental reason that missions like this are funded.
They've already spoken of having to totally re-think their gas giant model for Jupiter and have emphasized real-world measures are far preferred to remote modeling, so they're a bit surprised the models are so wrong.
To be clear, models are the core of modern science. I'm not sure what "real-world measures" are, other than observations that can support a model. The core knowledge does not come from the observations, but from the model (which is really just a complex kind of theory). The more observations the model matches, the more confidence you have in it. By increasing the number of different observations, they've greatly enhanced their ability to generate better models (which then lead to a richer understanding of the underlying phenomena).
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 2:30 am
by douglas
“We knew, going in, that Jupiter would throw us some curves,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio.
“There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.”
“It does look like Jupiter has a core, but it’s very large,” said Scott Bolton, Juno’s principal investigator based at the Southwest Research Institute. “It’s diffuse; it’s not as concentrated as we thought. We don’t know exactly how it gets that way.”
“The north pole doesn’t look like the south pole,” Bolton said. “We don’t completely understand that."
And the piece de resistance (this is what was meant, Chris):
"These preliminary data highlight the need for scientific instruments that can get up close and personal with their subject, said F. Michael Flasar, a planetary scientist at NASA Goddard who was not involved in the paper.
“The lesson I take from this is, if you want to learn something about these complex systems, you have to look at them,” Flasar said. “Because you’re not going to figure it out from first principles. You have to have data that sort of constrains your imagination ... because you’re going to see things you didn’t expect.”
Douglas, I'm sure everyone here is in agreement on "the need for scientific instruments that can get up close and personal".
The pre-Juno models of Jupiter are not developed from first principles alone. They are also based on a long history of observation and measurement. Juno is providing more and new observations and data, so that the models can be improved.
It is probably fair to say that the newspaper quotes you've listed are overstating things somewhat (shock). It is perhaps equally fair to say that Chris's statement: "No problems at all!" is also a bit of an overstatement, at least in some ways. But it would be a much, much bigger problem for the project scientists, if Juno had revealed nothing that wasn't already known. Juno isn't cheap.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 3:45 am
by Chris Peterson
Nitpicker wrote:It is perhaps equally fair to say that Chris's statement: "No problems at all!" is also a bit of an overstatement, at least in some ways.
I thought my point would be more clear, but perhaps not. I wasn't actually saying that the models themselves have no problems. Any but the most trivial models always have problems. What I meant by my statement was that finding problems in models isn't a problem for the scientists who are doing this work. That's what they live for. Not much is more exciting for a scientist than learning something new, than the opportunity to extend a theory.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 4:51 am
by Nitpicker
I agree Chris. I merely perceived a mix-up between good problems and bad problems. So I attempted to mediate, before it created an avoidable problem.
Erupting storm on Saturn. Image courtesy: SSI/CALTECH/NASA
Does Saturn have more internal heat than Jupiter? That seems strange and somehow contradictory to me. How do we measure it? And is anything known about the cause of it?
Perhaps it has something to do with the fact that there are stronger jet streams in Saturn than in Jupiter?
Ann
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 8:57 am
by Nitpicker
The numbers I can find suggest that the internal heat per unit area (W/m^2) emitted by Jupiter, is almost 3 times more than Saturn. Whether this is what Art means in his comparison of internal heat, I'm not sure.
Re: APOD: Beneath Jupiter (2017 May 29)
Posted: Wed May 31, 2017 12:32 pm
by neufer
Nitpicker wrote:
The numbers I can find suggest that the internal heat per unit area (W/m^2) emitted by Jupiter, is almost 3 times more than Saturn. Whether this is what Art means in his comparison of internal heat, I'm not sure.
Jupiter receives 3.37 times more external heat per unit area than Saturn.
Ergo...the Solar is less important for Saturn than Jupiter
(and your initial point vs-a-vis Saturn's axial tilt should be irrelevant).
Beneath Jupiter
