APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

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APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by APOD Robot » Mon Oct 07, 2019 4:07 am

Image Io Eclipse Shadow on Jupiter from Juno

Explanation: What's that dark spot on Jupiter? It's the shadow of Jupiter's most volcanic moon Io. Since Jupiter shines predominantly by reflected sunlight, anything that blocks that light leaves a shadow. If you could somehow be in that shadow, you would see a total eclipse of the Sun by Io. Io's shadow is about 3600 kilometers across, roughly the same size as Io itself -- and only slightly larger than Earth's Moon. The featured image was taken last month by NASA's robotic Juno spacecraft currently orbiting Jupiter. About every two months, Juno swoops close by Jupiter, takes a lot of data and snaps a series of images -- some of which are made into a video. Among many other things, Juno has been measuring Jupiter's gravitational field, finding surprising evidence that Jupiter may be mostly a liquid. Under unexpectedly thick clouds, the Jovian giant may house a massive liquid hydrogen region that extends all the way to the center.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by FLPhotoCatcher » Mon Oct 07, 2019 5:05 am

Wouldn't meteors that hit Jupiter sink to the center? And if they burned up, the heavier elements should still make their way to the center, right?

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Ann » Mon Oct 07, 2019 5:48 am

It has long been known that Saturn has a rocky core, and it has long been suspected that Jupiter may not have one.

So, because I'm too lazy to google, would someone enlighten me as to why Jupiter doesn't seem to have a rocky core?

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Chris Peterson » Mon Oct 07, 2019 5:50 am

FLPhotoCatcher wrote:
Mon Oct 07, 2019 5:05 am
Wouldn't meteors that hit Jupiter sink to the center? And if they burned up, the heavier elements should still make their way to the center, right?
All meteoroids hitting Jupiter burn up. Fine dust might remain suspended for very long periods of time; gases forever.
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by FLPhotoCatcher » Mon Oct 07, 2019 5:56 am

Chris Peterson wrote:
Mon Oct 07, 2019 5:50 am
FLPhotoCatcher wrote:
Mon Oct 07, 2019 5:05 am
Wouldn't meteors that hit Jupiter sink to the center? And if they burned up, the heavier elements should still make their way to the center, right?
All meteoroids hitting Jupiter burn up. Fine dust might remain suspended for very long periods of time; gases forever.
Being that hydrogen is the biggest fraction of the elements by far, and is the lightest element, shouldn't all the other gasses and elements sink? At least to the point where hydrogen becomes a liquid.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Henk Reints » Mon Oct 07, 2019 7:42 am

:?: Jupiter's radius is 38.4 times that of Io, so this shadow seems far too large to me, which would mean this image cannot be correct.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Boomer12k » Mon Oct 07, 2019 8:45 am

Henk Reints wrote:
Mon Oct 07, 2019 7:42 am
:?: Jupiter's radius is 38.4 times that of Io, so this shadow seems far too large to me, which would mean this image cannot be correct.
We are not seeing the whole of the face of Jupiter...but only a small fraction of it... we see it from a very close range. So we see a smaller horizon... as this is a close up shot... the shadow appears bigger...Take a large ball... hold it up away from you... now get real close... you will see LESS of the ball... like a beach ball... and you get real close...you might not even see the other colors of the beach ball if you were very up close to a blue area. It is the close up angle that blocks the view.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by JohnD » Mon Oct 07, 2019 9:01 am

Solar eclipses on Earth are accompanied by sudden temperature drops, as sunlight is removed - sudden night. This drop can be as much as 11 degrees, can be accompanied by an "eclipse wind", clouds can disappear and weather patterns change.

Some of this may be due to the Earth having a thin atmosphere over a solid (or liquid) surface. Was there any evidence of a change in Jupiter's thick atmosphere following the passage of Io, or any of its other moons?

John


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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by orin stepanek » Mon Oct 07, 2019 11:30 am

JupiterShadow_JunoGill_1080.jpg
Io's shadow on Jupiter! Fascinating view! I've always had the idea that Io was a little moon; but it really isn't. Maybe it's because that Jupiter is so very, very large! Just imagine; if Jupiter was a star; all her moons would be planets, (dwarfs?) and we would be in a double star system! :mrgreen:
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by neufer » Mon Oct 07, 2019 12:14 pm

https://en.wikipedia.org/wiki/2010:_Odyssey_Two wrote:
<<2010: Odyssey Two is a 1982 science fiction novel by British writer Arthur C. Clarke. It is the sequel to the 1968 novel 2001: A Space Odyssey, but continues the story of Stanley Kubrick's film adaptation with the same title rather than Clarke's original novel, which differed from the film in some respects. Set in the year 2010, the plot centres on a joint Soviet-American mission aboard the Soviet spacecraft The Cosmonaut Alexei Leonov. The mission has several objectives, including salvaging the spaceship Discovery and investigating the mysterious "monolith" discovered by Dave Bowman in 2001: A Space Odyssey.


...The Leonov crew flees Jupiter as a mysterious dark spot appears on Jupiter and begins to grow. HAL's telescope observations reveal that the "Great Black Spot" is, in fact, a vast population of monoliths, increasing at an exponential rate, which appear to be eating the planet. By acting as self-replicating machines, these monoliths increase Jupiter's density until the planet achieves nuclear fusion, becoming a small star. This obliterates the primitive life forms inhabiting the Jovian atmosphere, which the Monoliths' controllers had deemed highly unlikely to ever achieve intelligence, unlike the aquatic life of Europa.

As Jupiter is about to transform, Bowman returns to Discovery to give HAL a last order to carry out. HAL begins repeatedly broadcasting the message
ALL THESE WORLDS ARE YOURS – EXCEPT EUROPA.
ATTEMPT NO LANDINGS THERE.

The creation of the new star, which Earth eventually names Lucifer, destroys Discovery. However, in appreciation for HAL's help, Bowman has the aliens which control the monoliths remove HAL's artificial intelligence from Discovery's computer core and transform him into the same kind of life form as David Bowman, and become his companion.

The book ends with a brief epilogue, which takes place in AD 20,001. By this time, the Europans have evolved into a species that has developed a primitive civilisation, most likely with assistance from a monolith. They are not described in detail, though they are said to have "tendril"-like limbs. They regard the star Lucifer (formerly the planet Jupiter) as their primary sun, referring to Sol as "The Cold Sun". Though their settlements are concentrated primarily in the hemisphere of Europa which is constantly bathed in Lucifer's rays, some Europans have begun in recent generations to explore the Farside, the hemisphere facing away from Lucifer, which is still covered in ice. There they may witness the spectacle of night, unknown on the other side of Europa, when the Cold Sun sets.

The Europans who explore the Farside have been carefully observing the night sky and have begun to develop a mythology based on their observations. They correctly believe that Lucifer was not always there. They believe that the Cold Sun was its brother and was condemned to march around the sky for a crime. The Europans also see three other major bodies in the sky. One seems to be constantly engulfed in fire, and the other two have lights on them which are gradually spreading. These three bodies are the moons Io, Callisto, and Ganymede, the latter two of which are presently being colonised by humans.

Humans have been attempting to explore Europa ever since Lucifer was created in 2010. However, none of these attempts has been successful. Every probe that has attempted to land on Europa has been destroyed on approach. The debris from every probe falls to the surface of the planet, and the debris from some of the first ships to be destroyed is venerated by the Europans.

Finally, there is a Monolith on the planet, which is worshipped by the Europans more than anything else. The Europans assume, correctly, that the Monolith is what keeps humans at bay. Dave Bowman and HAL lie dormant in this Monolith. The Monolith is the guardian of Europa, and will continue to prevent contact between humans and Europans for as long as it sees fit.>>
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Tszabeau » Mon Oct 07, 2019 12:46 pm

“Since Jupiter shines predominantly by reflected sunlight,...” is that implying that Jupiter shines, to some degree, with its’ own light?

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Chris Peterson » Mon Oct 07, 2019 1:24 pm

FLPhotoCatcher wrote:
Mon Oct 07, 2019 5:56 am
Chris Peterson wrote:
Mon Oct 07, 2019 5:50 am
FLPhotoCatcher wrote:
Mon Oct 07, 2019 5:05 am
Wouldn't meteors that hit Jupiter sink to the center? And if they burned up, the heavier elements should still make their way to the center, right?
All meteoroids hitting Jupiter burn up. Fine dust might remain suspended for very long periods of time; gases forever.
Being that hydrogen is the biggest fraction of the elements by far, and is the lightest element, shouldn't all the other gasses and elements sink? At least to the point where hydrogen becomes a liquid.
Because there is mixing. (Note that we are not dying in a layer of carbon dioxide on our own planet, despite it being heavier than oxygen.)
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Chris Peterson » Mon Oct 07, 2019 1:26 pm

Tszabeau wrote:
Mon Oct 07, 2019 12:46 pm
“Since Jupiter shines predominantly by reflected sunlight,...” is that implying that Jupiter shines, to some degree, with its’ own light?
It certainly glows in infrared light that comes from more than simple re-radiating of the Sun's input.
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by JohnD » Mon Oct 07, 2019 1:30 pm

Jupiter glows in the infra-red: https://www.youtube.com/watch?v=0EH293DuwcE

and has some spectacular aurorae - thisd is in ultar-violet, but they are in visible light also: https://www.youtube.com/watch?v=xpAuuWHldNU

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by neufer » Mon Oct 07, 2019 1:52 pm

JohnD wrote:
Mon Oct 07, 2019 1:30 pm
Chris Peterson wrote:
Mon Oct 07, 2019 1:26 pm
Tszabeau wrote:
Mon Oct 07, 2019 12:46 pm

“Since Jupiter shines predominantly by reflected sunlight,...” is that implying that Jupiter shines, to some degree, with its’ own light?
It certainly glows in infrared light that comes from more than simple re-radiating of the Sun's input.
Jupiter glows in the infra-red: https://www.youtube.com/watch?v=0EH293DuwcE

and has some spectacular aurorae - this is in ultra-violet, but they are in visible light also: https://www.youtube.com/watch?v=xpAuuWHldNU
https://www.nasa.gov/feature/jpl/juno-solves-39-year-old-mystery-of-jupiter-lightning wrote:
Juno Solves 39-Year Old Mystery of Jupiter Lightning
NASA June 6, 2018

“No matter what planet you’re on, lightning bolts act like radio transmitters -- sending out radio waves when they flash across a sky,” said Shannon Brown of NASA’s Jet Propulsion Laboratory in Pasadena, California, a Juno scientist and lead author of the paper. “But until Juno, all the lightning signals recorded by spacecraft [Voyagers 1 and 2, Galileo, Cassini] were limited to either visual detections or from the kilohertz range of the radio spectrum, despite a search for signals in the megahertz range. Many theories were offered up to explain it, but no one theory could ever get traction as the answer.”

Enter Juno, which has been orbiting Jupiter since July 4, 2016. Among its suite of highly sensitive instruments is the Microwave Radiometer Instrument (MWR), which records emissions from the gas giant across a wide spectrum of frequencies.

“In the data from our first eight flybys, Juno’s MWR detected 377 lightning discharges,” said Brown. “They were recorded in the megahertz as well as gigahertz range, which is what you can find with terrestrial lightning emissions. We think the reason we are the only ones who can see it is because Juno is flying closer to the lighting than ever before, and we are searching at a radio frequency that passes easily through Jupiter’s ionosphere.” “Jupiter lightning distribution is inside out relative to Earth,” said Brown. “There is a lot of activity near Jupiter’s poles but none near the equator. You can ask anybody who lives in the tropics -- this doesn’t hold true for our planet.”

Why do lightning bolts congregate near the equator on Earth and near the poles on Jupiter? Follow the heat.

Earth’s derives the vast majority of its heat externally from solar radiation, courtesy of our Sun. Because our equator bears the brunt of this sunshine, warm moist air rises (through convection) more freely there, which fuels towering thunderstorms that produce lightning.>>
Art Neuendorffer

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by TheOtherBruce » Mon Oct 07, 2019 4:13 pm

Ann wrote:
Mon Oct 07, 2019 5:48 am
It has long been known that Saturn has a rocky core, and it has long been suspected that Jupiter may not have one.

So, because I'm too lazy to google, would someone enlighten me as to why Jupiter doesn't seem to have a rocky core?
The Wikipedia page on Jupiter suggests any original core could have been eroded by convection currents of liquid metallic hydrogen; there might or might not be anything left of it. As always, though, we need more data to figure it out for sure.

One of the fascinating points for me is that the actual gaseous atmosphere of Jupiter appears to be just a thin top layer, like the Earth's atmosphere. The deep regions outside the core (if there is one) are metallic hydrogen, compressed until it behaves like a metal, even though it's hot enough to be a liquid. In between it's a kind of fluid, not really gas or liquid, just getting denser as you go deeper. No weirder than the Earth's internal structure, I suppose.
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by BDanielMayfield » Mon Oct 07, 2019 5:54 pm

Boomer12k wrote:
Mon Oct 07, 2019 8:45 am
Henk Reints wrote:
Mon Oct 07, 2019 7:42 am
:?: Jupiter's radius is 38.4 times that of Io, so this shadow seems far too large to me, which would mean this image cannot be correct.
We are not seeing the whole of the face of Jupiter...but only a small fraction of it... we see it from a very close range. So we see a smaller horizon... as this is a close up shot... the shadow appears bigger...Take a large ball... hold it up away from you... now get real close... you will see LESS of the ball... like a beach ball... and you get real close...you might not even see the other colors of the beach ball if you were very up close to a blue area. It is the close up angle that blocks the view.

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That is a very good explanation Boomer. (Just thought it deserved some recognition.)
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by BDanielMayfield » Mon Oct 07, 2019 6:06 pm

TheOtherBruce wrote:
Mon Oct 07, 2019 4:13 pm
Ann wrote:
Mon Oct 07, 2019 5:48 am
It has long been known that Saturn has a rocky core, and it has long been suspected that Jupiter may not have one.

So, because I'm too lazy to google, would someone enlighten me as to why Jupiter doesn't seem to have a rocky core?
The Wikipedia page on Jupiter suggests any original core could have been eroded by convection currents of liquid metallic hydrogen; there might or might not be anything left of it. As always, though, we need more data to figure it out for sure.

One of the fascinating points for me is that the actual gaseous atmosphere of Jupiter appears to be just a thin top layer, like the Earth's atmosphere. The deep regions outside the core (if there is one) are metallic hydrogen, compressed until it behaves like a metal, even though it's hot enough to be a liquid. In between it's a kind of fluid, not really gas or liquid, just getting denser as you go deeper. No weirder than the Earth's internal structure, I suppose.
I did some reading also to find an answer to Ann's question, (not being too lazy to google), but I was too lazy to post a reply. Happily though TheOtherBruce has made up for my lapse. You're a credit to our name sir!

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by TheOtherBruce » Mon Oct 07, 2019 8:08 pm

BDanielMayfield wrote:
Mon Oct 07, 2019 6:06 pm
I did some reading also to find an answer to Ann's question, (not being too lazy to google), but I was too lazy to post a reply. Happily though TheOtherBruce has made up for my lapse. You're a credit to our name sir!
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by MarkBour » Mon Oct 07, 2019 8:56 pm

TheOtherBruce wrote:
Mon Oct 07, 2019 8:08 pm
BDanielMayfield wrote:
Mon Oct 07, 2019 6:06 pm
I did some reading also to find an answer to Ann's question, (not being too lazy to google), but I was too lazy to post a reply. Happily though TheOtherBruce has made up for my lapse. You're a credit to our name sir!
<raises hat, bops self on nose with one of the corks tied to the brim>
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by TheOtherBruce » Mon Oct 07, 2019 9:02 pm

Heh — I've been waiting months for the chance to slip in that particiular Pythonism. :wink:
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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by soynelson » Mon Oct 07, 2019 9:42 pm

La "fotografía" es un despropósito. Ni la "sombra" de Io es tan gigantesca, ni el horizonte joviano es tal, ni las "bandas" que se interrumpen hacia la derecha para dar lugar a "bandas" transversales son posibles. Todo parece una "travesura" de los muchachos de APOD.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by Cousin Ricky » Mon Oct 07, 2019 9:58 pm

soynelson wrote:
Mon Oct 07, 2019 9:42 pm
La "fotografía" es un despropósito. Ni la "sombra" de Io es tan gigantesca, ni el horizonte joviano es tal, ni las "bandas" que se interrumpen hacia la derecha para dar lugar a "bandas" transversales son posibles. Todo parece una "travesura" de los muchachos de APOD.
Favor de leer la respuesta de Boomer12k.

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Re: APOD: Io Eclipse Shadow on Jupiter from Juno (2019 Oct 07)

Post by soynelson » Mon Oct 07, 2019 10:40 pm

Cousin Ricky wrote:
Mon Oct 07, 2019 9:58 pm
Favor de leer la respuesta de Boomer12k.
Ya la había leído. No se cumplen las leyes de la perspectiva. En el símil de "la pelota de playa", al acercarse las proporciones varían, pero siempre bajo las leyes de la perspectiva. Si no se da, como en este caso, no son dichas leyes las equivocadas, sino que la imagen es "equívoca".
Respecto a las "bandas" que se discontinúan hacia la derecha y dan lugar a "bandas" transversales, nada se ha dicho. Que se muestre una sola fotografía de Júpiter (hay miles) donde estas bandas no sean circulares y prácticamente paralelas al ecuador joviano.
Saludos cordiales.