APOD: Jupiter from the Webb Space Telescope (2022 Aug 30)

[APOD Robot]

Jupiter from the Webb Space Telescope

Explanation: This new view of Jupiter is illuminating. High-resolution infrared images of Jupiter from the new James Webb Space Telescope (Webb) reveal, for example, previously unknown differences between high-floating bright clouds -- including the Great Red Spot -- and low-lying dark clouds. Also clearly visible in the featured Webb image are Jupiter's dust ring, bright auroras at the poles, and Jupiter's moons Amalthea and Adrastea. Large volcanic moon Io's magnetic funneling of charged particles onto Jupiter is also visible in the southern aurora. Some objects are so bright that light noticeably diffracts around Webb's optics creating streaks. Webb, which orbits the Sun<a/> near the Earth, has a mirror over 6 meters across making it the <a href="https://en.wikipedia.org/wiki/List_of_largest_optical_reflecting_telescopes">largest astronomical telescope ever launched -- with 15 times more light-collecting area than Hubble.

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[Ann]

That's a stunning image! Thanks, JWST and Geck!

Jupiter from the Webb Space Telescope. Image Credit: NASA, ESA, CSA, Jupiter ERS Team; Processing: Ricardo Hueso (UPV/EHU) & Judy Schmidt.

---

What I find most curious about the annotated image is "Io's footprint" (look at the writing just above Jupiter's southern aurora in the annotated image).

Footprint emoji.png (3.09 KiB) Viewed 11702 times

What does that mean? Well, the caption sort of explains it to us:

APOD Robot wrote:
Large volcanic moon Io's magnetic funneling of charged particles onto Jupiter is also visible in the southern aurora.

Stephan Schlegel, Joachim Saur wrote in a paper published in JGR Space Physics:

Io's movement relative to the plasma in Jupiter's magnetosphere creates Alfvén waves propagating along the magnetic field lines which are partially reflected along their path. These waves are the root cause for auroral emission, which is subdivided into the Io Footprint (IFP), its tail and leading spot.

I can only partially wrap my head around that wording, but I think I understand this: Io plays a pivotal role in creating the auroras on Jupiter.

---

Well, Io is giving Jupiter more than sulfur - it is giving it sparkling beautiful auroras! Read more about the picture from Planet Pailly here.

Ann

[bystander]

viewtopic.php?p=325349#p325349

[sc02492]

The phrase "with 15 times more light-collecting area" as currently written in the caption can be misinterpreted. It refers to field of view, which is a function of the scope's focal length and the camera's sensor size. It is true that JWST has a field of view (how much sky it can capture in a single image) that is 15 times greater than that of Hubble. However, the actual "light collecting area" of JWST's mirror compared to that of Hubble's is (6.5/2.4)^2, which is 7.33 times greater.

Steve

Steve Cannistra
www.starrywonders.com

[orin stepanek]

Beautiful; but I'm gonna have to get used to infrared images!

Kitty shocked!

[RJN]

The phrase "with 15 times more light-collecting area" as currently written in the caption can be misinterpreted. It refers to field of view, which is a function of the scope's focal length and the camera's sensor size. It is true that JWST has a field of view (how much sky it can capture in a single image) that is 15 times greater than that of Hubble. However, the actual "light collecting area" of JWST's mirror compared to that of Hubble's is (6.5/2.4)^2, which is 7.33 times greater.

Steve

Steve Cannistra
www.starrywonders.com

Yes thank you. My oversight. I have now corrected the text in the main NASA APOD changing "15" to "over six".
- RJN

[De58te]

A couple of questions. I read that the JWT can't detect blue visible color, being an infrared camera. So that means that the blue auroras aren't actually a blue color. Does blue mean that it a colder infrared which would make sense since the poles would be colder than the equator. But why is there a blue ring around the planets sides or equatorial regions? Probably because it is the upper atmosphere which is losing heat to space. I think I see that the blue is brighter on the left side than on the right. In the right side there is a narrow dark ring separating the planet's main surface from the upper atmosphere. What is that? Could it be that Jupiter is rotating counterclockwise and the right side has warmer air because it was exposed to the daylight, whereas on the left side it is coming from the cold night side?

[bystander]

A couple of questions. I read that the JWT can't detect blue visible color, being an infrared camera. So that means that the blue auroras aren't actually a blue color. Does blue mean that it a colder infrared which would make sense since the poles would be colder than the equator. But why is there a blue ring around the planets sides or equatorial regions? Probably because it is the upper atmosphere which is losing heat to space. I think I see that the blue is brighter on the left side than on the right. In the right side there is a narrow dark ring separating the planet's main surface from the upper atmosphere. What is that? Could it be that Jupiter is rotating counterclockwise and the right side has warmer air because it was exposed to the daylight, whereas on the left side it is coming from the cold night side?

None of what you see is natural color, the image is shot through two near infrared filters (JWST NIRCam), F212N (orange) and F335M (cyan).

[Chris Peterson]

A couple of questions. I read that the JWT can't detect blue visible color, being an infrared camera. So that means that the blue auroras aren't actually a blue color. Does blue mean that it a colder infrared which would make sense since the poles would be colder than the equator. But why is there a blue ring around the planets sides or equatorial regions? Probably because it is the upper atmosphere which is losing heat to space. I think I see that the blue is brighter on the left side than on the right. In the right side there is a narrow dark ring separating the planet's main surface from the upper atmosphere. What is that? Could it be that Jupiter is rotating counterclockwise and the right side has warmer air because it was exposed to the daylight, whereas on the left side it is coming from the cold night side?

None of what you see is natural color, the image is shot through two near infrared filters (JWST NIRCam), F212N (orange) and F335M (cyan).

And even that is not a great way of putting it. The F212N channel has its signal split in some way between the red and green output channels, and the F335M channel has its signal split in some way between the blue and green channels. While such a mapping may produce an aesthetically pleasing image, it is generally a bad idea for any scientific analysis, since it irreversibly conflates the two source channels, resulting in a loss of information. As a rule, it is best if no output (display) channel contains data from more than one input (sensor) channel.

[johnnydeep]

I second Ann's perplexity about "Io's shadow". I'm still not sure what that really is, or means, or even what the arrow in the pic is pointing to (if meant to refer to something other than the southern aurora).

[Everyone knows it's red. RED!]

Marvellous, fantastic, extraordinary, visually quite arresting, but the Great White Spot will take some getting used to.

[alter-ego]

I second Ann's perplexity about "Io's shadow". I'm still not sure what that really is, or means, or even what the arrow in the pic is pointing to (if meant to refer to something other than the southern aurora).

Though fairly complicated, here's a simplified explanation. It's not a new thing, and I must admit I don't recall reading about it before.

...
But Jupiter has something we don't: a volcanically active moon. Io spews sulfur from a series of volcanoes on its surface. The sulfur atoms go up into space, get ionized, and interact with Jupiter's magnetic field as well. Waves of electromagnetic energy are created, and these travel along the magnetic field lines, slamming into Jupiter's atmosphere. Io is, in a way, connected to Jupiter, and you can see this connection, literally, as a bright spot of ultraviolet light on Jupiter.
...

[geckzilla]

A couple of questions. I read that the JWT can't detect blue visible color, being an infrared camera. So that means that the blue auroras aren't actually a blue color. Does blue mean that it a colder infrared which would make sense since the poles would be colder than the equator. But why is there a blue ring around the planets sides or equatorial regions? Probably because it is the upper atmosphere which is losing heat to space. I think I see that the blue is brighter on the left side than on the right. In the right side there is a narrow dark ring separating the planet's main surface from the upper atmosphere. What is that? Could it be that Jupiter is rotating counterclockwise and the right side has warmer air because it was exposed to the daylight, whereas on the left side it is coming from the cold night side?

None of what you see is natural color, the image is shot through two near infrared filters (JWST NIRCam), F212N (orange) and F335M (cyan).

And even that is not a great way of putting it. The F212N channel has its signal split in some way between the red and green output channels, and the F335M channel has its signal split in some way between the blue and green channels. While such a mapping may produce an aesthetically pleasing image, it is generally a bad idea for any scientific analysis, since it irreversibly conflates the two source channels, resulting in a loss of information. As a rule, it is best if no output (display) channel contains data from more than one input (sensor) channel.

FWIW the way I process a 2 color image generally does not conflate the two filters at least not in the red and blue channel. Only the green channel is a mix of the two. In this case however in F335M there were a lot of dark spots that look like data drop out for whatever reason (I'm actually not sure why, cosmic rays?) and to get around that I generated the color image and then used the luminosity of F212N.

No one should be doing science with *any* of my images. Period. If anyone even thinks about it I'll just direct them straight to the FITS files which they should have known in the first place.

I've attached an image showing what it looks like with the filters in chromatic order and without the cosmetic solution that caused them to become conflated.

[Ann]

I second Ann's perplexity about "Io's shadow". I'm still not sure what that really is, or means, or even what the arrow in the pic is pointing to (if meant to refer to something other than the southern aurora).

Though fairly complicated, here's a simplified explanation. It's not a new thing, and I must admit I don't recall reading about it before.

...
But Jupiter has something we don't: a volcanically active moon. Io spews sulfur from a series of volcanoes on its surface. The sulfur atoms go up into space, get ionized, and interact with Jupiter's magnetic field as well. Waves of electromagnetic energy are created, and these travel along the magnetic field lines, slamming into Jupiter's atmosphere. Io is, in a way, connected to Jupiter, and you can see this connection, literally, as a bright spot of ultraviolet light on Jupiter.
...

Click to view full size image

Very interesting, alter-ego. Thanks!

If you don't mind, I'm going to quote from the Discover article to explain what we see in the illustration:

Phil Plait of Bad Astronomy wrote in Discover:

Here's what they think is happening: Io blasts sulfur into space. This forms a torus, a doughnut-shaped region of plasma surrounding Jupiter (yellow-green in the illustration above). The magnetic field of the giant planet ionizes the sulfur.

As Jupiter's magnetic field whips past Io, it connects with the moon, and waves of energy flow from Io to Jupiter, creating the bright footprint spot and trail (not shown, but the stream is in blue).

The spot is connected to its opposite-hemisphere counterpart by the electron beam (shown in red), and that's what creates the leading, fainter spot.

The "main spot" would be Io's footprint on Jupiter. The "leading spot" would be
the spot hit by the electron beam from its opposite-hemisphere counterpart.

Jupiter's aurora. My guess is that the bright spot at far left might be Io's footprint.

---

Ann

[Chris Peterson]

None of what you see is natural color, the image is shot through two near infrared filters (JWST NIRCam), F212N (orange) and F335M (cyan).

And even that is not a great way of putting it. The F212N channel has its signal split in some way between the red and green output channels, and the F335M channel has its signal split in some way between the blue and green channels. While such a mapping may produce an aesthetically pleasing image, it is generally a bad idea for any scientific analysis, since it irreversibly conflates the two source channels, resulting in a loss of information. As a rule, it is best if no output (display) channel contains data from more than one input (sensor) channel.

No one should be doing science with *any* of my images. Period. If anyone even thinks about it I'll just direct them straight to the FITS files which they should have known in the first place.

Exactly, Geck! Which is something I regularly remind people of when they get a bit too... obsessed... with the colors found in images here.

There's absolutely nothing wrong with mixing channels in a way that gives an aesthetically pleasing result. And there's absolutely nothing wrong with doing so in a way that reveals some kind of structure or detail that isn't as easily seen in the individual channels by themselves. But in the final scientific analysis, it is those individual channels that we have to analyze.

[johnnydeep]

Thanks alter-ego and Ann for the further explanation of what "Io's shadow" is. Seems to be quite a complex phenomenon!