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Compare Webb's Images to Hubble

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Re: Compare Webb's Images to Hubble

#81

Post by ryneandal »

red_trumpet wrote: post #32
dynm wrote: post #26

Question for anyone who happens to be an expert: Is there any way to quantify how much better Webb is independently of the amount of time used to take the exposures? Like, could Hubble achieve the same quality of images as Webb if it was given 100x (or whatever) more time exposure? I'm trying to understand how much the improvement is "speed of convergence" vs. "quality of asymptotic result". (Though... is that even a…

I'm no expert either, but I imagine that high exposure times come with more motion blur. So just cranking up exposure time does not necessarily result in better pictures.

Here's out exposure time works for JWST: https://jwst-docs.stsci.edu/understanding-exposure-times

Re: Compare Webb's Images to Hubble

#82

Post by rdsubhas »

dynm wrote: post #26

Question for anyone who happens to be an expert: Is there any way to quantify how much better Webb is independently of the amount of time used to take the exposures? Like, could Hubble achieve the same quality of images as Webb if it was given 100x (or whatever) more time exposure? I'm trying to understand how much the improvement is "speed of convergence" vs. "quality of asymptotic result". (Though... is that even a…

A crude analogy is like this: Two cameras are pointed towards a wall. Camera #1 is good, but it is blocked by the wall. Camera #2 has a special trick, it does some magic that can look behind the wall.

Now both have resolutions and stuff. But no matter how big the resolution or how long it stares, cam1 is fundamentally blocked by the wall. It can take extremely high res photos of things inside the wall, but it can never see anything behind the wall.

Cam2 could have infinitely higher quality than cam1 — because who knows, there can be 100, 1000, million or a never ending world of things behind that wall that can never be seen or captured by cam1.

Cam1 is Hubble, cam2 is JWST, and the wall is infrared wavelength which is all around us. JWST can peer deeper into the _same area_ of space, and see more things behind the infrared wall, which Hubble can never see.

Re: Compare Webb's Images to Hubble

#83

Post by mtlmtlmtlmtl »

supernova87a wrote: post #61

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 differe…

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.

Re: Compare Webb's Images to Hubble

#84

Post by dylan604 »

throwaway4837 wrote: post #73
avelis wrote: post #66

To touch the stars. To reach a galaxy. To dream of afar. And in the deepest space, see our ancestry.

It's hard to look at the Webb images without thinking that there must be life and technology out somewhere else in the stars.

Why does that only come from Webb images? You weren't getting that same sensation looking at the Hubble images before? If that's true, then welcome to the club! It took you a bit longer, but we're happy you're here now. ;P

Re: Compare Webb's Images to Hubble

#85

Post by dylan604 »

tambourine_man wrote: post #11
laserbeam wrote: post #7

Earlier quoted context omitted.

It's my understanding that Webb used much shorter exposure times than Hubble, correct?

Yes, hours vs days, which makes them a lot more impressive if you know a bit about photography. I wanna see what this thing is able to do with a 10 days exposure. Let it loose.

>I wanna see what this thing is able to do with a 10 days exposure.

Ever seen a solid white square? =)

As with all things, it totally depends on what's being imaged. Exposing the Orion Nebula for 10 days would result in a totally over exposed image looking like a solid white square.

Re: Compare Webb's Images to Hubble

#86

Post by dylan604 »

bandyaboot wrote: post #29

I’m curious what’s going on in the upper left area of the Carina Nebula image. The dust can’t have actually cleared out that much since the Hubble shot was taken, could it?

Lots of visible light is reflected in the Hubble image from the dust causing it to look like it does. As others have said, the JWST does not suffer from that as it "sees" past those frequencies revealing new details instead.

Re: Compare Webb's Images to Hubble

#87

Post by lynguist »

masterspy7 wrote: post #51

Not trying to underscore this incredible achievement, but I'm curious if we could use AI techniques to upscale the Hubble images to achieve similar results as the Webb telescope. Has this been tried before?

It’s a valid thought, but it would really be like trying to take pictures of the sky from underwater and using AI to make it look like it was taken from out of water.

This means: the AI has to predict what it is supposed to look like and for that we would need out of water pictures as reference in the first place which we didn’t so far!

And then: even if we have these new out of water pictures as reference, the AI generated ones would still not show what is real, but instead a fiction. The fiction can look believable but it cannot be studied to derive facts from it. It’s like trying to study an AI generated language.

This sounds like my friend who literally believes that buses will go extinct within 3-5 years as every vehicle will self drive. It’s not thought all the way through.

Re: Compare Webb's Images to Hubble

#88

Post by tigershark »

supernova87a wrote: post #61

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 differe…

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.

Re: Compare Webb's Images to Hubble

#89

Post by lisper »

nacogo wrote: post #74
supernova87a wrote: post #61

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 differe…

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/

Yes, exactly right. (AFAIK, IANAA)

Re: Compare Webb's Images to Hubble

#90

Post by bastardoperator »

Downvote me to hell, but as a person who has zero understanding of what differentiates Hubble from Webb, the pictures alone just aren't doing it for me. I was excited to see something completely new given 30 years and 10 billion dollars and instead I feel like I'm seeing what looks like an enterprise upgrade and feel slightly disappointed.

What am I missing?

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