Explanation: Ringed, ice giant Neptune lies near the center of this sharp near-infrared image from the James Webb Space Telescope. The dim and distant world is the farthest planet from the Sun, about 30 times farther away than planet Earth. But in the stunning Webb view the planet's dark and ghostly appearance is due to atmospheric methane that absorbs infrared light. High altitude clouds that reach above most of Neptune's absorbing methane easily stand out in the image though. Coated with frozen nitrogen, Neptune's largest moon Triton is brighter than Neptune in reflected sunlight and is seen at upper left sporting the Webb's characteristic diffraction spikes. Including Triton, seven of Neptune's 14 known moons can be identified in the field of view. Neptune's faint rings are striking in this new space-based planetary portrait. Details of the complex ring system are seen here for the first time since Neptune was visited by the Voyager 2 spacecraft in August 1989.
Explanation: Ringed, ice giant Neptune lies near the center of this sharp near-infrared image from the James Webb Space Telescope. The dim and distant world is the farthest planet from the Sun, about 30 times farther away than planet Earth. But in the stunning Webb view the planet's dark and ghostly appearance is due to atmospheric methane that absorbs infrared light. High altitude clouds that reach above most of Neptune's absorbing methane easily stand out in the image though. Coated with frozen nitrogen, Neptune's largest moon Triton is brighter than Neptune in reflected sunlight and is seen at upper left sporting the Webb's characteristic diffraction spikes. Including Triton, seven of Neptune's 14 known moons can be identified in the field of view. Neptune's faint rings are striking in this new space-based planetary portrait. Details of the complex ring system are seen here for the first time since Neptune was visited by the Voyager 2 spacecraft in August 1989.
I would not describe Neptune's appearance here as "dark", and indeed, it has diffraction spikes about the same length as those of Triton.. because it is so bright.
Explanation: Ringed, ice giant Neptune lies near the center of this sharp near-infrared image from the James Webb Space Telescope. The dim and distant world is the farthest planet from the Sun, about 30 times farther away than planet Earth. But in the stunning Webb view the planet's dark and ghostly appearance is due to atmospheric methane that absorbs infrared light. High altitude clouds that reach above most of Neptune's absorbing methane easily stand out in the image though. Coated with frozen nitrogen, Neptune's largest moon Triton is brighter than Neptune in reflected sunlight and is seen at upper left sporting the Webb's characteristic diffraction spikes. Including Triton, seven of Neptune's 14 known moons can be identified in the field of view. Neptune's faint rings are striking in this new space-based planetary portrait. Details of the complex ring system are seen here for the first time since Neptune was visited by the Voyager 2 spacecraft in August 1989.
I would not describe Neptune's appearance here as "dark", and indeed, it has diffraction spikes about the same length as those of Triton.. because it is so bright.
Indeed. Neptune's diffraction spikes are there, but they are much less obvious than the spikes of Triton, because they are broad and diffuse.
Ann
Re: APOD: Ringed Ice Giant Neptune (2022 Sep 23)
Posted: Fri Sep 23, 2022 5:16 am
by Ann
I have made a previous post about the James Webb picture of Neptune and Triton where I pointed out that Neptune looks fainter than Triton here for the same reason that Neptune looks blue in visible light. Neptune looks blue to our eyes because methane in its atmosphere absorbs and dims near infrared wavelengths, essentially robbing Neptune's outer layers of some red and infrared light.
But this is also exactly the reason why Neptune looks relatively dim at near infrared wavelengths and in this NIRCam image. Neptune reflects less infrared light back into space than it "should", because infrared light has been absorbed by methane in its atmosphere.
It is hard not to pay attention to brilliantly bright Triton in this picture. I highly recommend the video about Triton that you find below. Did you know that Triton is almost certainly a captured Kuiper Belt object that is bigger than Pluto, but in other respects very similar to Pluto?
I very much wanted to know the designation of the lovely barred spiral galaxy in the lower left corner, but I have found no information on it.
Background galaxy the field of Neptune on September 21, 2022.
This is what ESA/Webb wrote about the background galaxy seen in the field of Neptune:
ESA Webb wrote:
Towards the bottom left of this image, a barred spiral galaxy comes into focus. Scientists say this particular galaxy, previously unexplored in detail, is about 1,200 million light years away. These types of galaxies at this relative difference are typically dominated by young stars that appear blueish in these wavelengths.
I agree that the morphological type of the barred spiral background galaxy makes it look blue, not yellow. I think it is slightly similar to NGC 7479. Perhaps we may also compare it to NGC 1365, although NGC 1365 is a huge galaxy.
The tilt of Neptune seems reasonable in the new Webb images. Compare the Webb image above with the series of pictures of Uranus (top row) and Neptune (bottom row).
joe.fagan@outlook.com wrote: ↑Fri Sep 23, 2022 11:58 am
is Neptune picture tilted 90 deg on ?? spikes and rings should be tilted more , right ?
The tilt of Neptune seems reasonable in the new Webb images. Compare the Webb image above with the series of pictures of Uranus (top row) and Neptune (bottom row).
Yes, Neptune currently has its southern pole tipped our way. Which also means that the ring section at the top is in front of the planet, and the section at the bottom is behind it (which isn't terribly obvious in the image outside the geometry of it).
Re: APOD: Ringed Ice Giant Neptune (2022 Sep 23)
Posted: Fri Sep 23, 2022 4:23 pm
by VictorBorun
to enjoy Neptune's purple spikes I tried to block the planet with almost black tent:
There is a side effect: Neptune's equator can be seen more clearly
Re: APOD: Ringed Ice Giant Neptune (2022 Sep 23)
Posted: Fri Sep 23, 2022 4:27 pm
by VictorBorun
they say a bright spot near Neptune's South Pole is really a background star almost eclipsed by Neptune:
Ann wrote: ↑Fri Sep 23, 2022 9:23 am
I very much wanted to know the designation of the lovely barred spiral galaxy in the lower left corner, but I have found no information on it.
Explanation: Ringed, ice giant Neptune lies near the center of this sharp near-infrared image from the James Webb Space Telescope. The dim and distant world is the farthest planet from the Sun, about 30 times farther away than planet Earth. But in the stunning Webb view the planet's dark and ghostly appearance is due to atmospheric methane that absorbs infrared light. High altitude clouds that reach above most of Neptune's absorbing methane easily stand out in the image though. Coated with frozen nitrogen, Neptune's largest moon Triton is brighter than Neptune in reflected sunlight and is seen at upper left sporting the Webb's characteristic diffraction spikes. Including Triton, seven of Neptune's 14 known moons can be identified in the field of view. Neptune's faint rings are striking in this new space-based planetary portrait. Details of the complex ring system are seen here for the first time since Neptune was visited by the Voyager 2 spacecraft in August 1989.
I would not describe Neptune's appearance here as "dark", and indeed, it has diffraction spikes about the same length as those of Triton.. because it is so bright.
Neptune diffraction spikes NIRCAM annotated.png
Indeed. Neptune's diffraction spikes are there, but they are much less obvious than the spikes of Triton, because they are broad and diffuse.
Ann
It looks like the diffraction spikes on Neptune could be due more to the bright rim than to the darker methane-induced IR-absorbing body. No?
in fact I got it wrong. I thought Ethan Siegel meant this bright spot at the rim of Neptune's disk:Neptune STScI-01GCCVK522S3SWM0TJN2ZA02ZZ-.jpg
Neptune STScI-01GCCVK522S3SWM0TJN2ZA02ZZ -2.jpg
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Chris Peterson wrote: ↑Fri Sep 23, 2022 4:19 am
I would not describe Neptune's appearance here as "dark", and indeed, it has diffraction spikes about the same length as those of Triton.. because it is so bright.
Neptune diffraction spikes NIRCAM annotated.png
Indeed. Neptune's diffraction spikes are there, but they are much less obvious than the spikes of Triton, because they are broad and diffuse.
Ann
It looks like the diffraction spikes on Neptune could be due more to the bright rim than to the darker methane-induced IR-absorbing body. No?
There are many confusing things about the image. The spikes appear almost entirely in the blue channel, but that represents the shortest wavelengths, in the near-IR, where Neptune is supposed to be not very bright. Yet we see a bright white rim that suggests large amounts of near-IR as well as thermal-IR.
As always, trying to understand what's really going on is difficult or impossible using a color image like this. We really need to go back to the individual channels that the color image is constructed from. (In this case there are four source channels mapped onto three output channels, which represents an irreversible convolution of the data.)
Re: APOD: Ringed Ice Giant Neptune (2022 Sep 23)
Posted: Fri Sep 23, 2022 11:41 pm
by heehaw
Neptune. Yes. Neptune. Must put that on my list....
Re: APOD: Ringed Ice Giant Neptune (2022 Sep 23)
Posted: Fri Sep 23, 2022 11:43 pm
by heehaw
heehaw wrote: ↑Fri Sep 23, 2022 11:41 pm
Neptune. Yes. Neptune. Must put that on my list....
Indeed. Neptune's diffraction spikes are there, but they are much less obvious than the spikes of Triton, because they are broad and diffuse.
Ann
It looks like the diffraction spikes on Neptune could be due more to the bright rim than to the darker methane-induced IR-absorbing body. No?
There are many confusing things about the image. The spikes appear almost entirely in the blue channel, but that represents the shortest wavelengths, in the near-IR, where Neptune is supposed to be not very bright. Yet we see a bright white rim that suggests large amounts of near-IR as well as thermal-IR.
As always, trying to understand what's really going on is difficult or impossible using a color image like this. We really need to go back to the individual channels that the color image is constructed from. (In this case there are four source channels mapped onto three output channels, which represents an irreversible convolution of the data.)
Back when Hubble Heritage was active, and they published one new Heritage image every month, they used to show the individual channels, too. So we could see what the target in question looked like in (for example) the B, V and near infrared channels.
Ann wrote: ↑Fri Sep 23, 2022 9:23 am
I very much wanted to know the designation of the lovely barred spiral galaxy in the lower left corner, but I have found no information on it.
Interesting: The image below shows that a survey of Jupiter was previously made with Hubble at almost the same position. The fact that Jupiter (HST) appears about 6 times too large compared to the image of Neptune (JWST) is due to the difference in the spatial positions of the planets and the telescopes at different times.
Ann wrote: ↑Fri Sep 23, 2022 9:23 am
I very much wanted to know the designation of the lovely barred spiral galaxy in the lower left corner, but I have found no information on it.
Interesting: The image below shows that a survey of Jupiter was previously made with Hubble at almost the same position. The fact that Jupiter (HST) appears about 6 times too large compared to the image of Neptune (JWST) is due to the difference in the spatial positions of the planets and the telescopes at different times.
To show planets side by side we have to compensate for their distance and for a dimmer illumination.
To show galaxies side by side we have to compensate for their angular distance and red shift (and age, if we dare simulate their ageing).
Ann wrote: ↑Fri Sep 23, 2022 9:23 am
I very much wanted to know the designation of the lovely barred spiral galaxy in the lower left corner, but I have found no information on it.
Interesting: The image below shows that a survey of Jupiter was previously made with Hubble at almost the same position. The fact that Jupiter (HST) appears about 6 times too large compared to the image of Neptune (JWST) is due to the difference in the spatial positions of the planets and the telescopes at different times.
Thank you, RET and AVAO, for identifying the beautiful barred galaxy!
AVAO, I'm not sure I understand what you mean by Jupiter being 6 times too large compared with Neptune in the HST image compared with the JWST image. Isn't Neptune almost 6 times farther away than Jupiter, and doesn't that have to make it look much smaller?
Ringed Ice Giant Neptune
