<p>OK, this seems to be a real thing (that is, it's probably not some image-processing/enhancement artifact), and is <em>probably</em> due to high-level atmospheric haze and possibly also due to Jupiter's shadow... but as far as I can tell, it's still rather mysterious.</p>
<p>In <a href="https://youtu.be/oMbeCKh-9v4" rel="noreferrer">this video interview with planetary scientist Heidi Hammel</a>, you can see her getting excited about this feature in early JWST images (<a href="https://youtu.be/oMbeCKh-9v4?t=319" rel="noreferrer">this</a> is the point in the video (5:19) where she starts talking about the feature, ending around 6:12.)</p>
<p>From about the same time (October 2022), there are a couple of relevant abstracts of talks at the 54th AAS Division for Planetary Sciences meeting (early October, 2024) which reference this &quot;detached haze layer&quot; phenomenon.</p>
<p><a href="https://baas.aas.org/pub/2022n8i306p07/release/1" rel="noreferrer">&quot;JWST Observations of the Jovian System from Commissioning and ERS data&quot;, by Imke de Pater et al.</a> has the following:</p>
<blockquote>
<p>NIRCam images of Jupiter show an incredible amount of detail over the
Jupiter disc in images at 2.12 and 3.23 microns sensitive to
tropospheric and stratospheric hazes. Both wavelength images revealed
an intriguing illuminated layer above the dusk terminator: there is an
ongoing debate about the origins of this feature, potentially caused
by stratospheric hazes or H3+ emissions (see also Sromovsky et al).</p>
</blockquote>
<p>The referenced talk by &quot;Sromovsky et al.&quot; is <a href="https://baas.aas.org/pub/2022n8i306p08/release/1" rel="noreferrer">&quot;JWST Near-IR observations of a mysterious detached haze layer on Jupiter&quot;</a>; some excerpts:</p>
<blockquote>
<p>... we found that the “detached haze” feature on the opposite (shaded)
terminator limb fell within the shadow of Jupiter and only about 200
km above the 1 bar level. This suggests either a remarkable coincident
alignment of two unrelated phenomena or that the “detached haze” may
in fact be the same haze inferred from modeling the illuminated disk,
with an altitude closer to 160 km. The problem with the latter
interpretation is that the haze should not be visible in the dark! All
the indirect illumination options we have investigated so far fall far
short of producing the observed brightness of the shaded feature,
which is about an order of magnitude dimmer than the peak of the
directly illuminated haze (on the sunlit limb). Perhaps what appears
to be a shadowed haze is actually a molecular emission of some sort,
but the feature’s altitude seems to be much too low for H3+ emissions.
This mystery has so far defied explanation.</p>
</blockquote>
<p>(Note that the Sromovsky et al. abstract consistently refers to the shaded side with the detached haze feature [i.e., the right side in the image] as the &quot;east&quot; side, which I <em>think</em> is wrong, as standard astronomical image orientation means that east is to the left and west is to the right; in addition, the <a href="https://www.aanda.org/articles/aa/full_html/2024/11/aa51453-24/F3.html" rel="noreferrer">Figure 3 caption</a> for <a href="https://www.aanda.org/articles/aa/full_html/2024/11/aa51453-24/aa51453-24.html" rel="noreferrer">Rodríguez-Ovalle et al. (2024)</a> refers to this as the &quot;west&quot; limb.)</p>
<p>This figure is from the Sromovsky et al. abstract:</p>
<p><a href="https://i.sstatic.net/WiCLIu7w.png" rel="noreferrer"><img src="https://i.sstatic.net/WiCLIu7w.png" alt="JWST image of left and right limbs of Jupiter, showing &quot;stratospheric haze peak in sunlight&quot; on the left and &quot;detached haze layer in Jupiter's shadow&quot; on the right." /></a></p>
<p>I haven't been able to find any subsequent published research on this, which might indicate one of several things: 1) It's been determined that this actually is some kind of (telescopic) imaging artifact; 2) People have been busy with other data analysis and modeling of JWST Jupiter observations; 3) They're waiting on more and better data, such as spectroscopy. In support of the latter possibility, I'll note that there was an approved Cycle 2 JWST proposal (<a href="https://www.stsci.edu/jwst/science-execution/program-information?id=3665" rel="noreferrer">&quot;Unveiling Jupiter’s upper atmosphere and constraining atmospheric loss
from Giant Planets&quot;</a>) using the NIRSpec Integral Field Unit spectrograph that might be useful (&quot;The observations proposed here will investigate the vertical distribution of the molecular ion H3+ above the limb of Jupiter.&quot;) The data for the latter were taken about a year ago; since they're probably pretty complicated to analyze and model, it doesn't surprise me at all that nothing's been published yet.</p>
<p>So perhaps we'll hear more about this &quot;mystery [that] has so far defied explanation&quot; in another year or so.</p>

CC BY-SA 4.0
2024-11-14T10:59:19.240Z
2024-11-14T11:07:43.023Z
2024-11-14T11:07:43.023Z
Peter Erwin
<p><a href="https://i.sstatic.net/DdjB7KA4.jpg" rel="noreferrer"><img src="https://i.sstatic.net/DdjB7KA4.jpg" alt="" /></a>
[Source: NASA/Webb]</p>
<p>On the rightmost edge of Jupiter, there is a black layer between the planet and the very top of its atmosphere.</p>
<ul>
<li><p>Is this the day-night terminator effect, like when the clouds above are still bright after the sunset?</p>
</li>
<li><p>Is it Jupiter's huge magnetic field causing auroras even near the equator?</p>
</li>
<li><p>Is there a transparent layer just below the top, optically-dense layer?</p>
</li>
<li><p>Does stuff in the top of Jupiter's atmosphere make it just glow, like glow in the dark paint (re-emiting absorbed photons at a specific wavelength)?</p>
</li>
<li><p>Is it some kind of IR optical aberration, like when the left edge of Jupiter looked red in my 4&quot; Tasco and the right edge looked blue?</p>
</li>
</ul>
<p>It's thickest at the equator and thins out and disappears at the poles. That might be a hint.</p>

CC BY-SA 4.0
2024-11-12T17:05:39.407Z
Or is it some kind of imaging artefact?
PM 2Ring
CC BY-SA 4.0
2024-11-12T17:08:50.373Z
What's the source of that Jupiter image? Please give proper attribution of any images (or other material) that you post that isn't your own work.
PM 2Ring
CC BY-SA 4.0
2024-11-12T17:16:45.780Z
Thanks. If you *don't* give attribution, people may repost your images & anims and give *you* credit, under the CC BY-SA licence...
PM 2Ring
CC BY-SA 4.0
2024-11-12T18:22:19.770Z
I would place my money on imaging artifact indeed. It looks like someone used the “Unsharp Mask” effect/filter a little too much, or something similar.
Pierre Paquette
CC BY-SA 4.0
2024-11-12T19:34:51.040Z
Photos of earth under the right conditions have a similar effect because of the sodium layer, where ionized sodium on the edge of the atmosphere makes a band of streetlight-yellow.  I expect this is a layer of gas that ionizes at that particular altitude and emits a sharp spectral line in the infrared.
Darth Pseudonym
CC BY-SA 4.0
2024-11-13T00:19:52.153Z
Where was this published? Without any details of how it was recorded,  processed, and rendered, all anybody can do is guess.
John Doty
CC BY-SA 4.0
2024-11-13T02:54:20.763Z
Is Jupiter supposed to luminate like that?
Nilay Ghosh
CC BY-SA 4.0
2024-11-13T03:13:23.700Z
It's an infrared photo of Jupiter taken from webb. That's all I know.
Miss Understands
CC BY-SA 4.0
2024-11-13T06:56:09.370Z
@JohnDoty [The New York Times](https://www.nytimes.com/2022/08/23/science/james-webb-telescope-jupiter-galaxies.html) stated "*A composite image of the Jupiter system taken by the James Webb Space Telescope’s NIRCam using two filters, F212N (orange) and F335M (cyan). Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Ricardo Hueso and Judy Schmidt*"
Andrew T.
CC BY-SA 4.0
2024-11-13T12:45:52.143Z
@AndrewT. No details about the processing given. The details matter.
John Doty
CC BY-SA 4.0
2024-11-13T12:49:19.787Z
@AndrewT. >  No details about the processing given. === Well, That does it! That closes the matter. Feel free to downvote and close the stupid question. I was just curious what the black line in Jupiter's atmosphere was, but never mind.
Miss Understands
CC BY-SA 4.0
2024-11-13T22:12:22.480Z
It's not a stupid question. It's quite a good question. We just might not have the information to answer it. I want to note that there's another shot in the [NASA blog post about these photos](https://blogs.nasa.gov/webb/2022/08/22/webbs-jupiter-images-showcase-auroras-hazes/) that also shows the same line under a different set of filters.
Darth Pseudonym
CC BY-SA 4.0
2024-11-13T23:46:21.580Z
From the article linked by @DarthPseudonym , the outermost band may well be Jupiter's very faint ring system rather than Jupiter's atmosphere. If this is the case, there is a gap between the ring system and the atmosphere, and this gap is  of course black. That's just a guess on my part, so I am not making it an answer. But that guess certainly does jibe with the text of the linked article.
David Hammen
CC BY-SA 4.0
2024-11-14T03:47:13.740Z
I don't think it's rings. The label is a little confusing in one of the photos but it's referring to the equatorial rings as you'd expect, not the ... whatever it is that's visible north-to-south for most of the limb on the darker side.
Darth Pseudonym
CC BY-SA 4.0
2024-11-14T03:49:06.427Z
@Miss_Understands: Actually, it looks more like a layer combination error. It looks like they were trying to emphasize detail somewhere else in the picture, and this came out as an artefact.
Pierre Paquette
CC BY-SA 4.0
2024-11-14T07:47:39.133Z
@PierrePaquette I’m skeptical that’s it’s an unsharp mask artifact or a “layer combination error”; for one thing, why isn’t it there on the left side of Jupiter as well?
Peter Erwin
CC BY-SA 4.0
2024-11-16T00:23:29.397Z
@PeterErwin: Well, the question is even more à propos if it’s a natural thing on Jupiter. It would be everywhere around it, not just on the right. An imaging/processing artifact could result from miscentered layers or stuff like that.
Pierre Paquette
<jupiter><planetary-atmosphere><james-webb-space-telescope><infrared>
What is the black gap layer in Jupiter's limb?
Miss Understands
# What is the black gap layer in Jupiter's limb?

(Asked by: username_0 on 2024-11-12)

[![](https://i.sstatic.net/DdjB7KA4.jpg)](https://i.sstatic.net/DdjB7KA4.jpg)
[Source: NASA/Webb]

On the rightmost edge of Jupiter, there is a black layer between the planet and the very top of its atmosphere.

* Is this the day-night terminator effect, like when the clouds above are still bright after the sunset?
* Is it Jupiter's huge magnetic field causing auroras even near the equator?
* Is there a transparent layer just below the top, optically-dense layer?
* Does stuff in the top of Jupiter's atmosphere make it just glow, like glow in the dark paint (re-emiting absorbed photons at a specific wavelength)?
* Is it some kind of IR optical aberration, like when the left edge of Jupiter looked red in my 4" Tasco and the right edge looked blue?

It's thickest at the equator and thins out and disappears at the poles. That might be a hint.

**Tags:** jupiter, planetary-atmosphere, james-webb-space-telescope, infrared
> **Comments:**
> **username_1**: Or is it some kind of imaging artefact?  
> **username_1**: What's the source of that Jupiter image? Please give proper attribution of any images (or other material) that you post that isn't your own work.  
> **username_1**: Thanks. If you *don't* give attribution, people may repost your images & anims and give *you* credit, under the CC BY-SA licence...  
> **username_2**: I would place my money on imaging artifact indeed. It looks like someone used the “Unsharp Mask” effect/filter a little too much, or something similar.  
> **username_3**: Photos of earth under the right conditions have a similar effect because of the sodium layer, where ionized sodium on the edge of the atmosphere makes a band of streetlight-yellow.  I expect this is a layer of gas that ionizes at that particular altitude and emits a sharp spectral line in the infrared.  
> **username_4**: Where was this published? Without any details of how it was recorded,  processed, and rendered, all anybody can do is guess.  
> **username_5**: Is Jupiter supposed to luminate like that?  
> **username_0**: It's an infrared photo of Jupiter taken from webb. That's all I know.  
> **username_6**: @JohnDoty [The New York Times](https://www.nytimes.com/2022/08/23/science/james-webb-telescope-jupiter-galaxies.html) stated "*A composite image of the Jupiter system taken by the James Webb Space Telescope’s NIRCam using two filters, F212N (orange) and F335M (cyan). Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Ricardo Hueso and Judy Schmidt*"  
> **username_4**: @AndrewT. No details about the processing given. The details matter.  
> **username_0**: @AndrewT. >  No details about the processing given. === Well, That does it! That closes the matter. Feel free to downvote and close the stupid question. I was just curious what the black line in Jupiter's atmosphere was, but never mind.  
> **username_3**: It's not a stupid question. It's quite a good question. We just might not have the information to answer it. I want to note that there's another shot in the [NASA blog post about these photos](https://blogs.nasa.gov/webb/2022/08/22/webbs-jupiter-images-showcase-auroras-hazes/) that also shows the same line under a different set of filters.  
> **username_7**: From the article linked by @DarthPseudonym , the outermost band may well be Jupiter's very faint ring system rather than Jupiter's atmosphere. If this is the case, there is a gap between the ring system and the atmosphere, and this gap is  of course black. That's just a guess on my part, so I am not making it an answer. But that guess certainly does jibe with the text of the linked article.  
> **username_3**: I don't think it's rings. The label is a little confusing in one of the photos but it's referring to the equatorial rings as you'd expect, not the ... whatever it is that's visible north-to-south for most of the limb on the darker side.  
> **username_2**: @Miss_Understands: Actually, it looks more like a layer combination error. It looks like they were trying to emphasize detail somewhere else in the picture, and this came out as an artefact.  
> **username_8**: @PierrePaquette I’m skeptical that’s it’s an unsharp mask artifact or a “layer combination error”; for one thing, why isn’t it there on the left side of Jupiter as well?  
> **username_2**: @PeterErwin: Well, the question is even more à propos if it’s a natural thing on Jupiter. It would be everywhere around it, not just on the right. An imaging/processing artifact could result from miscentered layers or stuff like that.  

---

## 1 answers

### Answer by username_8 on 2024-11-14. Score: 9

OK, this seems to be a real thing (that is, it's probably not some image-processing/enhancement artifact), and is *probably* due to high-level atmospheric haze and possibly also due to Jupiter's shadow... but as far as I can tell, it's still rather mysterious.

In [this video interview with planetary scientist Heidi Hammel](https://youtu.be/oMbeCKh-9v4), you can see her getting excited about this feature in early JWST images ([this](https://youtu.be/oMbeCKh-9v4?t=319) is the point in the video (5:19) where she starts talking about the feature, ending around 6:12.)

From about the same time (October 2022), there are a couple of relevant abstracts of talks at the 54th AAS Division for Planetary Sciences meeting (early October, 2024) which reference this "detached haze layer" phenomenon.

["JWST Observations of the Jovian System from Commissioning and ERS data", by Imke de Pater et al.](https://baas.aas.org/pub/2022n8i306p07/release/1) has the following:

> NIRCam images of Jupiter show an incredible amount of detail over the
> Jupiter disc in images at 2.12 and 3.23 microns sensitive to
> tropospheric and stratospheric hazes. Both wavelength images revealed
> an intriguing illuminated layer above the dusk terminator: there is an
> ongoing debate about the origins of this feature, potentially caused
> by stratospheric hazes or H3+ emissions (see also Sromovsky et al).

The referenced talk by "Sromovsky et al." is ["JWST Near-IR observations of a mysterious detached haze layer on Jupiter"](https://baas.aas.org/pub/2022n8i306p08/release/1); some excerpts:

> ... we found that the “detached haze” feature on the opposite (shaded)
> terminator limb fell within the shadow of Jupiter and only about 200
> km above the 1 bar level. This suggests either a remarkable coincident
> alignment of two unrelated phenomena or that the “detached haze” may
> in fact be the same haze inferred from modeling the illuminated disk,
> with an altitude closer to 160 km. The problem with the latter
> interpretation is that the haze should not be visible in the dark! All
> the indirect illumination options we have investigated so far fall far
> short of producing the observed brightness of the shaded feature,
> which is about an order of magnitude dimmer than the peak of the
> directly illuminated haze (on the sunlit limb). Perhaps what appears
> to be a shadowed haze is actually a molecular emission of some sort,
> but the feature’s altitude seems to be much too low for H3+ emissions.
> This mystery has so far defied explanation.

(Note that the Sromovsky et al. abstract consistently refers to the shaded side with the detached haze feature [i.e., the right side in the image] as the "east" side, which I *think* is wrong, as standard astronomical image orientation means that east is to the left and west is to the right; in addition, the [Figure 3 caption](https://www.aanda.org/articles/aa/full_html/2024/11/aa51453-24/F3.html) for [Rodríguez-Ovalle et al. (2024)](https://www.aanda.org/articles/aa/full_html/2024/11/aa51453-24/aa51453-24.html) refers to this as the "west" limb.)

This figure is from the Sromovsky et al. abstract:

[![JWST image of left and right limbs of Jupiter, showing ](https://i.sstatic.net/WiCLIu7w.png)](https://i.sstatic.net/WiCLIu7w.png)

I haven't been able to find any subsequent published research on this, which might indicate one of several things: 1) It's been determined that this actually is some kind of (telescopic) imaging artifact; 2) People have been busy with other data analysis and modeling of JWST Jupiter observations; 3) They're waiting on more and better data, such as spectroscopy. In support of the latter possibility, I'll note that there was an approved Cycle 2 JWST proposal (["Unveiling Jupiter’s upper atmosphere and constraining atmospheric loss
from Giant Planets"](https://www.stsci.edu/jwst/science-execution/program-information?id=3665)) using the NIRSpec Integral Field Unit spectrograph that might be useful ("The observations proposed here will investigate the vertical distribution of the molecular ion H3+ above the limb of Jupiter.") The data for the latter were taken about a year ago; since they're probably pretty complicated to analyze and model, it doesn't surprise me at all that nothing's been published yet.

So perhaps we'll hear more about this "mystery [that] has so far defied explanation" in another year or so.


---

