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For the professional (or former professional) astronomers among us, I will make my somewhat amused observation that what people are most paying attention to is

For the professional (or former professional) astronomers among us, I will make my somewhat amused observation that what people are most paying attention to is not really the distinguishing features of JWST. People seem most impressed by the apparent increase in resolution of the images, which is not from a certain point of view the hardest thing to do . HST might have done that if its instruments had been of different pixel size or imaging array size / focal length. Ok, the much larger mirror is an achievement. But anyway, the resolution of the images is often not what really is the limiting factor for photometric observations. Yes it is sharper/higher resolution, but that wasn't the key selling point. The new thing is observations in the IR, which is somewhat a technical footnote in many gushing announcements of these images (or some discussion here too). And the general public knows little about that detail's importance, especially since the images are stylized / colored anyway to look just like RGB images that we are so familiar with. But everyone can easily appreciate a sharper image. Anyway, still a momentous achievement. And thank god we have a scientific field where stunning images was enough to get the public to support a $10B project. ** Edit to add: I did not mean to detract from or diminish anyone's appreciation of the images and accomplishment at whatever level they are enjoyed. And of course many here are technically knowledgeable about the IR aspect. I just write to point out that for the most headline-grabbing images and newspaper writers, the sharpness of the images over the actual IR frontier is what grabs the attention.

AQXt 4y ago
> especially since the images are stylized / colored anyway The thing that I don't like about the new images is the abuse of star flare effect. The colors are okay, but the flares... that's simply too much.
- tiagod 4y ago
  I don't think that's on purpose
- ygra 4y ago
  It's not an effect. It's a diffraction artifact that's a consequence of the telescope construction. Explained here for example: https://bigthink.com/starts-with-a-bang/james-webb-spikes/ https://bigthink.com/starts-with-a-bang/james-webb-spikes/
  - MeteorMarc 4y ago
    Although this reference nicely explains the origin of the diffraction pattern on the JWT images, it does not explain why the spikes seems to extend much farther then in the Hubble images. My hunge is that the JWT succeeds much better to gather all the light into a real point which makes the primary diffraction pattern stronger too. While this is very important for scientific work (easier to see planets!) it is less appealing to the eye. Also note that some JWT images have some faint blue streaks which in effect are diffraction spikes from bright stars outside the field of view.
nacogo 4y ago
Agreed! In the SMACS 0723 image, there is a red spiral galaxy near the top right which is effectively not present in the HST image because it was redshifted out of the spectrum. This implies it's one of the galaxies receding the fastest from us in the image right? And therefore also among the oldest and farthest away? https://blog.wolfd.me/hubble-jwst/ https://blog.wolfd.me/hubble-jwst/
- lisper 4y ago
  Yes, exactly right. (AFAIK, IANAA)
  - t3estabc 4y ago
- supernova87a 4y ago
  Yes, well 2 possible effects: 1) as you said, its flux is predominantly in the IR 2) it could have been fainter than the sensitivity of the HST instruments but now seen because of the sensitivity of JWST But given that it appears so bright in the JWST image similar to other nearby galaxies that do appear in the HST image, your bet on #1 seems reasonable. Also there is another point: rather than a highly redshifted galaxy it could be a very dusty nearby galaxy (also appearing very red) but if I remember right, that would have a slightly different signature. Dusty galaxies often aren't entirely dusty and have "lanes/channels/streaks" of dust that are interspersed among normal stellar regions, so if it were that, you would be seeing some bright spots outside the infrared. But this one has the shape of a normal galaxy but red all over, suggesting something affects the whole galaxy -- i.e. redshift.
  - importantbrian 4y ago
    Isn't there a 3rd possibility that the galaxy is quenched leaving only redder stars?
  - iampivot 4y ago
    Isn't one way to detect redshift to check if there's absorption of certain frequencies due to the light passing through matter on the way here? The absorption will be redshifted as well?
mtlmtlmtlmtl 4y ago
Right. After the initial "wow factor" has settled down, what's been most striking to me is the level of detail that's no longer obscured by gas and dust in these nebulae due to MIRI. I know very little about the study of stellar nurseries or planetary nebulae but I've seen enough pre-JWST images of them to know that astrophysicists just got a whole lot to sink their teeth into and I look forward to seeing further developments as more data is collected and existing data is studied.
tigershark 4y ago
The increased resolution is extremely important given that the diffraction threshold is function of the wavelength and the mirror diameter. And you can clearly see that in the MIRI images at a longer wavelength that have a noticeably lower resolution compared to Nircam. If Webb mirror was as big as Hubble the resolution would have been bad in the long wavelengths. Hubble couldn’t have had a better resolution with better instruments, he was already limited by its aberration problem and the new instruments were designed to mitigate that problem.
- supernova87a 4y ago
  Those are good points -- my original comment was a little simplistic. I don't have the info at hand -- do you know what was the resolution of HST optical/NIR imagers versus JWST new imagers?
libraryatnight 4y ago
- Enginerrrd 4y ago
  I think this is a little harsh, but I actually generally agree. I'm a total laymen here and my PRIMARY TAKEAWAY has been the IR component and how much more and further away you can see because of it.
  - Ensorceled 4y ago
    I get what you are trying to say here, but someone posting on HN about "the IR component" using the nom de guerre "Enginerrd" might not be "a total laymen" :-)
    - Enginerrrd 4y ago
      Ok, yeah, in retrospect that's probably fair.
- supernova87a 4y ago
  Apologies, I did not mean for it to come off that way. I edited it to not make such broad brush statements. Certainly people here and discussing it among those who get to watch these announcements during their day, are a more knowledgeable and appreciative group of the details. They have the time and info to know the "new" aspect. I was just making the point that in the most headline-grabbing and CNN/newspaper science-writer genre, probably their and their audience just sees the image sharpness as they flip through the news.
- Ensorceled 4y ago
  > This is so dismissive and insulting. ... I'm sure you were well intentioned, but this comment read all kinds of rude and negative. Your comment is way, way over the top. Their observation is entirely correct, maybe not in your circles, but certainly it's what I'm also seeing on Facebook and twitter. Hell, NASA posted "The razor-sharp resolution of the @NASAWebb imagery was enough to bring astrophysicist Jane Rigby to tears."
jstgord 4y ago
.. and why is infra-red more useful ? Can we see through dust or something ?
- foobarbecue 4y ago
  Infrared is the only way to see things that are cold (as in not a star) or extremely far away (due to redshift).
  - skybrian 4y ago
    What about reflected light, like most things we see in the solar system?
    - foobarbecue 4y ago
      Good point, I shouldn't have said "only." I have heard of reflected light been used for exoplanet observations although I think it's quite faint. I guess some nebulae are illuminated by stars. I don't know if the reflected light is longer wavelength than the incident light, but I suspect so. BTW I'm not an astronomer!
- bryananderson 4y ago
  Seeing through dust is part of it. Another part is redshift: because of relativity, things moving away from us appear redder (longer wavelength) the faster they’re moving away. That’s the same principle (Doppler effect) as the lower-pitched siren sound as the ambulance drives away. Because the universe itself is expanding, the farther something is from us, the faster it’s moving away relative to us, and the more redshifted it appears to us. And again because of relativity, the oldest objects we can see are the ones that appear farthest away (i.e. their light is just now getting here, after 13 billion years, from 13 billion light years away). Thus, if we want to study the earliest times of the universe, we must study the most redshifted objects—which have shifted all the way out of the visible spectrum and into the infrared. Hence, Webb is an infrared telescope.
  - 4y ago
Centmo 4y ago
Also, when comparing the deep field images I don't think it can be stressed enough the difference in exposure time between HST and JWST images (Hubble had a 10x longer exposure time). Many many more distant galaxies would become visible in the JWST image with the much longer exposure time. I look forward to seeing some long-exposure deep field images from JWST!
- kibwen 4y ago
  This is underappreciated. Much lamentation has been made of the fact that JWST's current mission length is only ten years (maybe twenty or thirty at best, but hard-limited by on-board coolant), but with the speed of its observations that ten years will be as productive as a century of Hubble time.
  - MichaelZuo 4y ago
    It's difficult to imagine how more detailed the JWST images could be if they used the same observation time as the Hubble images. Will there be thousands of additional extremely red shifted galaxies?
    - antisthenes 4y ago
      With a 10x observation time, you would probably be approaching a uniform cosmic background of multitudes of galaxies. There would be negligible space without a light emitter. > Will there be thousands of additional extremely red shifted galaxies? Yes, and also those that were too faint, but not necessarily extremely red-shifted.
ElThomaso 4y ago
In the second image it is clear that more of the nebula is visible, isn't this because more wavelengths of light are being detected? In this case an amateur absolutely can appreciate the technical improvements, the IR is mapped to a visible RGB spectrum...
- svachalek 4y ago
  Different wavelengths. The JWST also cannot see the shorter wavelengths that Hubble excels at.
undersuit 4y ago
I'm impressed by the speed of the imaging. Apparently the Hubble Deep Field took over 10 days of telescope time while JWST did it in 12.5 hours.
Helmut10001 4y ago
Well, also, one thing to note is that it took WEBB only hours to capture these images, while HUBBLE was aimed for days and months to capture comparable ones. It will be interesting to see the results when they have more time to capture longer sequences of light.
Cthulhu_ 4y ago
If I may get political here (nothing personal / no direct reply to the parent comment): > stunning images was enough to get the public to support a $10B project. I don't believe public support is relevant; is there public support for the >$700B a year spent on the military?
- dQw4w9WgXcQ 4y ago
  > is there public support for the >$700B a year spent on the military? Of course. It's tempting to think we're in this new lovey-dovey age of an improved/superior humanity, but the reality is man's baser instincts are kept in check by BFGs and MAD.
- TulliusCicero 4y ago
  Yeah, more or less. People gripe about it occasionally, especially on the left, but then some shit will go down like Ukraine and suddenly nobody wants to look like an idiot (which will absolutely happen in an American context if you suggest cutting military spending right after Russia invades someone).
- dtgriscom 4y ago
  Public support for NASA drives the members of Congress to allocate funds for its work. So, NASA spends a whole lot of effort showing the public how cool its work is. That, and it divides its facilities and subcontractors across the various states to ensure that every member of congress has constituents who benefit from its payroll.
- neuronic 4y ago
  >$700B Global force projection at the benefit for all Western economies is very expensive. This money is required to even allow the form of economy "the West" is running. How else were you going to keep up the Pax Americana that enables globalization by making significant global trade networks even possible in the first place? Who's gonna insure your freighter if international waters aren't protected by Western navies? Pirates, rogue states closing important channels, at will seizures for no reason... the list is long. As the Pax Americana will likely soon fade through growing influence of the BRICS nations and "America First"-style ideologies, the 700B will probably wither away quite fast in the next decades - along with all the benefits we enjoyed since WW2. Just one illustration. How man South American or African nations support the sanctions against Russia? How many Asian nations that are not Japan?
gliptic 4y ago
> HST might have done that if its instruments had been of different pixel size or imaging array size / focal length HST is already imaging at diffraction-limited resolution (with proper post-processing). It would need a bigger mirror to get there.
nabla9 4y ago
>The new thing is observations in the IR, Not a new thing. Herschel space observatory operated in same location (L2-point) as JWST and it was IR telescope. https://www.google.com/search?q=Herschel+space+observatory+images&hl=en https://www.google.com/search?q=Herschel+space+observatory+i... Mirror sizes: Hubble 4.0 m2 (43 sq ft) Herschel 9.6 m2 (103 sq ft) JWST 25.4 m2 (273 sq ft) Hubble had ~40% of the Herschel's collecting area and Herchel had 40% of the JWST's collecting area.
- supernova87a 4y ago
  That is a good point -- my simplification of the advance provided by JWST is aimed at saying, JWST is kind of the first major telescope with such depth and resolution to complement the deep fields of HST that everyone is so familiar with. Herschel, while impressive also, was far-IR (if I recall) and much lower resolution, which was good for certain research areas, but less complementary to the HST deep fields for the, well, currently fashionable, recent study of galaxies at high redshift.

AQXt 4y ago

> especially since the images are stylized / colored anyway The thing that I don't like about the new images is the abuse of star flare effect. The colors are okay, but the flares... that's simply too much.

tiagod 4y ago
I don't think that's on purpose
ygra 4y ago
It's not an effect. It's a diffraction artifact that's a consequence of the telescope construction. Explained here for example: https://bigthink.com/starts-with-a-bang/james-webb-spikes/ https://bigthink.com/starts-with-a-bang/james-webb-spikes/
- MeteorMarc 4y ago
  Although this reference nicely explains the origin of the diffraction pattern on the JWT images, it does not explain why the spikes seems to extend much farther then in the Hubble images. My hunge is that the JWT succeeds much better to gather all the light into a real point which makes the primary diffraction pattern stronger too. While this is very important for scientific work (easier to see planets!) it is less appealing to the eye. Also note that some JWT images have some faint blue streaks which in effect are diffraction spikes from bright stars outside the field of view.

nacogo 4y ago

Agreed! In the SMACS 0723 image, there is a red spiral galaxy near the top right which is effectively not present in the HST image because it was redshifted out of the spectrum. This implies it's one of the galaxies receding the fastest from us in the image right? And therefore also among the oldest and farthest away? https://blog.wolfd.me/hubble-jwst/ https://blog.wolfd.me/hubble-jwst/

lisper 4y ago
Yes, exactly right. (AFAIK, IANAA)
- t3estabc 4y ago
supernova87a 4y ago
Yes, well 2 possible effects: 1) as you said, its flux is predominantly in the IR 2) it could have been fainter than the sensitivity of the HST instruments but now seen because of the sensitivity of JWST But given that it appears so bright in the JWST image similar to other nearby galaxies that do appear in the HST image, your bet on #1 seems reasonable. Also there is another point: rather than a highly redshifted galaxy it could be a very dusty nearby galaxy (also appearing very red) but if I remember right, that would have a slightly different signature. Dusty galaxies often aren't entirely dusty and have "lanes/channels/streaks" of dust that are interspersed among normal stellar regions, so if it were that, you would be seeing some bright spots outside the infrared. But this one has the shape of a normal galaxy but red all over, suggesting something affects the whole galaxy -- i.e. redshift.
- importantbrian 4y ago
  Isn't there a 3rd possibility that the galaxy is quenched leaving only redder stars?
- iampivot 4y ago
  Isn't one way to detect redshift to check if there's absorption of certain frequencies due to the light passing through matter on the way here? The absorption will be redshifted as well?

mtlmtlmtlmtl 4y ago

Right. After the initial "wow factor" has settled down, what's been most striking to me is the level of detail that's no longer obscured by gas and dust in these nebulae due to MIRI. I know very little about the study of stellar nurseries or planetary nebulae but I've seen enough pre-JWST images of them to know that astrophysicists just got a whole lot to sink their teeth into and I look forward to seeing further developments as more data is collected and existing data is studied.

tigershark 4y ago

The increased resolution is extremely important given that the diffraction threshold is function of the wavelength and the mirror diameter. And you can clearly see that in the MIRI images at a longer wavelength that have a noticeably lower resolution compared to Nircam. If Webb mirror was as big as Hubble the resolution would have been bad in the long wavelengths. Hubble couldn’t have had a better resolution with better instruments, he was already limited by its aberration problem and the new instruments were designed to mitigate that problem.

supernova87a 4y ago
Those are good points -- my original comment was a little simplistic. I don't have the info at hand -- do you know what was the resolution of HST optical/NIR imagers versus JWST new imagers?

libraryatnight 4y ago

Enginerrrd 4y ago
I think this is a little harsh, but I actually generally agree. I'm a total laymen here and my PRIMARY TAKEAWAY has been the IR component and how much more and further away you can see because of it.
- Ensorceled 4y ago
  I get what you are trying to say here, but someone posting on HN about "the IR component" using the nom de guerre "Enginerrd" might not be "a total laymen" :-)
  - Enginerrrd 4y ago
    Ok, yeah, in retrospect that's probably fair.
supernova87a 4y ago
Apologies, I did not mean for it to come off that way. I edited it to not make such broad brush statements. Certainly people here and discussing it among those who get to watch these announcements during their day, are a more knowledgeable and appreciative group of the details. They have the time and info to know the "new" aspect. I was just making the point that in the most headline-grabbing and CNN/newspaper science-writer genre, probably their and their audience just sees the image sharpness as they flip through the news.
Ensorceled 4y ago
> This is so dismissive and insulting. ... I'm sure you were well intentioned, but this comment read all kinds of rude and negative. Your comment is way, way over the top. Their observation is entirely correct, maybe not in your circles, but certainly it's what I'm also seeing on Facebook and twitter. Hell, NASA posted "The razor-sharp resolution of the @NASAWebb imagery was enough to bring astrophysicist Jane Rigby to tears."

jstgord 4y ago

.. and why is infra-red more useful ? Can we see through dust or something ?

foobarbecue 4y ago
Infrared is the only way to see things that are cold (as in not a star) or extremely far away (due to redshift).
- skybrian 4y ago
  What about reflected light, like most things we see in the solar system?
  - foobarbecue 4y ago
    Good point, I shouldn't have said "only." I have heard of reflected light been used for exoplanet observations although I think it's quite faint. I guess some nebulae are illuminated by stars. I don't know if the reflected light is longer wavelength than the incident light, but I suspect so. BTW I'm not an astronomer!
bryananderson 4y ago
Seeing through dust is part of it. Another part is redshift: because of relativity, things moving away from us appear redder (longer wavelength) the faster they’re moving away. That’s the same principle (Doppler effect) as the lower-pitched siren sound as the ambulance drives away. Because the universe itself is expanding, the farther something is from us, the faster it’s moving away relative to us, and the more redshifted it appears to us. And again because of relativity, the oldest objects we can see are the ones that appear farthest away (i.e. their light is just now getting here, after 13 billion years, from 13 billion light years away). Thus, if we want to study the earliest times of the universe, we must study the most redshifted objects—which have shifted all the way out of the visible spectrum and into the infrared. Hence, Webb is an infrared telescope.
- 4y ago

Centmo 4y ago

Also, when comparing the deep field images I don't think it can be stressed enough the difference in exposure time between HST and JWST images (Hubble had a 10x longer exposure time). Many many more distant galaxies would become visible in the JWST image with the much longer exposure time. I look forward to seeing some long-exposure deep field images from JWST!

kibwen 4y ago
This is underappreciated. Much lamentation has been made of the fact that JWST's current mission length is only ten years (maybe twenty or thirty at best, but hard-limited by on-board coolant), but with the speed of its observations that ten years will be as productive as a century of Hubble time.
- MichaelZuo 4y ago
  It's difficult to imagine how more detailed the JWST images could be if they used the same observation time as the Hubble images. Will there be thousands of additional extremely red shifted galaxies?
  - antisthenes 4y ago
    With a 10x observation time, you would probably be approaching a uniform cosmic background of multitudes of galaxies. There would be negligible space without a light emitter. > Will there be thousands of additional extremely red shifted galaxies? Yes, and also those that were too faint, but not necessarily extremely red-shifted.

ElThomaso 4y ago

In the second image it is clear that more of the nebula is visible, isn't this because more wavelengths of light are being detected? In this case an amateur absolutely can appreciate the technical improvements, the IR is mapped to a visible RGB spectrum...

svachalek 4y ago
Different wavelengths. The JWST also cannot see the shorter wavelengths that Hubble excels at.

undersuit 4y ago

I'm impressed by the speed of the imaging. Apparently the Hubble Deep Field took over 10 days of telescope time while JWST did it in 12.5 hours.

Helmut10001 4y ago

Well, also, one thing to note is that it took WEBB only hours to capture these images, while HUBBLE was aimed for days and months to capture comparable ones. It will be interesting to see the results when they have more time to capture longer sequences of light.

Cthulhu_ 4y ago

If I may get political here (nothing personal / no direct reply to the parent comment): > stunning images was enough to get the public to support a $10B project. I don't believe public support is relevant; is there public support for the >$700B a year spent on the military?

dQw4w9WgXcQ 4y ago
> is there public support for the >$700B a year spent on the military? Of course. It's tempting to think we're in this new lovey-dovey age of an improved/superior humanity, but the reality is man's baser instincts are kept in check by BFGs and MAD.
TulliusCicero 4y ago
Yeah, more or less. People gripe about it occasionally, especially on the left, but then some shit will go down like Ukraine and suddenly nobody wants to look like an idiot (which will absolutely happen in an American context if you suggest cutting military spending right after Russia invades someone).
dtgriscom 4y ago
Public support for NASA drives the members of Congress to allocate funds for its work. So, NASA spends a whole lot of effort showing the public how cool its work is. That, and it divides its facilities and subcontractors across the various states to ensure that every member of congress has constituents who benefit from its payroll.
neuronic 4y ago
>$700B Global force projection at the benefit for all Western economies is very expensive. This money is required to even allow the form of economy "the West" is running. How else were you going to keep up the Pax Americana that enables globalization by making significant global trade networks even possible in the first place? Who's gonna insure your freighter if international waters aren't protected by Western navies? Pirates, rogue states closing important channels, at will seizures for no reason... the list is long. As the Pax Americana will likely soon fade through growing influence of the BRICS nations and "America First"-style ideologies, the 700B will probably wither away quite fast in the next decades - along with all the benefits we enjoyed since WW2. Just one illustration. How man South American or African nations support the sanctions against Russia? How many Asian nations that are not Japan?

gliptic 4y ago

> HST might have done that if its instruments had been of different pixel size or imaging array size / focal length HST is already imaging at diffraction-limited resolution (with proper post-processing). It would need a bigger mirror to get there.

nabla9 4y ago

>The new thing is observations in the IR, Not a new thing. Herschel space observatory operated in same location (L2-point) as JWST and it was IR telescope. https://www.google.com/search?q=Herschel+space+observatory+images&hl=en https://www.google.com/search?q=Herschel+space+observatory+i... Mirror sizes: Hubble 4.0 m2 (43 sq ft) Herschel 9.6 m2 (103 sq ft) JWST 25.4 m2 (273 sq ft) Hubble had ~40% of the Herschel's collecting area and Herchel had 40% of the JWST's collecting area.

supernova87a 4y ago
That is a good point -- my simplification of the advance provided by JWST is aimed at saying, JWST is kind of the first major telescope with such depth and resolution to complement the deep fields of HST that everyone is so familiar with. Herschel, while impressive also, was far-IR (if I recall) and much lower resolution, which was good for certain research areas, but less complementary to the HST deep fields for the, well, currently fashionable, recent study of galaxies at high redshift.