Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Compare Webb's Images to Hubble

johnedchristensen.github.io

Post reply on HN
Print view View original

171–180 of 254 posts

Re: Compare Webb's Images to Hubble

#171

Post by Balgair »

lynguist wrote: post #87
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 ge…

Like, I guess you could run images and tensors through a neural net and see what the weights look like. That might tell you something that the endless pool of astro-grad students missed. Like, maaaaaaaybe you might have backed out dark matter from some strangely weighted neuron, or there might be something lurking in the noise that was missed. But, I really really doubt it.

Re: Compare Webb's Images to Hubble

#173

Post by dotancohen »

bryananderson wrote: post #124
jstgord wrote: post #109

Earlier quoted context omitted.

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

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 reds…

Your statements about redshift and distance are correct, but I do not see where relativity comes into it. Even in Newtonian physics redshift occurs. If you could elaborate I would love to learn. Thank you!

Re: Compare Webb's Images to Hubble

#174

Post by rkagerer »

soulofmischief wrote: post #135
mortenjorck wrote: post #134

Earlier quoted context omitted.

Related question: to confirm, some of the additional detail we’re seeing in the JWST images is in fact IR that has been “hue clamped” into the visible spectrum?

It's all IR. It's color-mapped over RGB, but the sensors are IR.

Didn't the observed light shift into IR wavelengths due to the expansion of space over the last billions of years while it traveled to us?

Do the recolored images have any relation to what the original view would have looked like, or is it just arbitrary "artistic license"?

Re: Compare Webb's Images to Hubble

#175

Post by akira2501 »

laserbeam wrote: post #7
thatswrong0 wrote: post #5

Just needs to include exposure time differences and this is perfect. Glad to witness the power of this fully armed and operational battle station.

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

Exposure time on Webb is complicated. The sensors are different, the sampling techniques are different, and you can get the on board systems to do integration within sets of exposures for you.

https://jwst-docs.stsci.edu/understanding-exposure-times

Re: Compare Webb's Images to Hubble

#176

Post by gcbirzan »

mtlmtlmtlmtl wrote: post #47
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…

IANA{astrophysicist, space engineer} but I do follow this closely and have what I call a working armchair understanding of this stuff. Anyone from relevant fields is welcome to gently correct any imprecisions. I always want to learn more and will thank you for it >could Hubble achieve the same quality of images as Webb if it was given 100x (or whatever) more time exposure? No, for a different and simpler reason: Hubb…

> This also will see much older light which is redshifted(the longer the travel, the greater the shift) out of Hubble's range of sensitivity.

It's a matter of speed not distance, isn't it?

Re: Compare Webb's Images to Hubble

#177

Post by izacus »

SCAQTony wrote: post #122

Aesthetically, I like the Hubble images better, they are more painterly and colorful. However there is no doubt that the JWST contains way more information and is exponentially more valuable.

Ummm, pretty much all of those images are artificially colored so your comment basically just judges the person postprocessing the images and applying colors for detected wavelengths.

Re: Compare Webb's Images to Hubble

#178

Post by justanotherme »

A question to the experts here: What will be the most exciting things to be explored within the next months? What insight could come out of it, which open questions could be answered? Hints to life on other planets by observing specific spectrums of specific ones? Could certain open questions about the early universe be decided? Or something else?

Re: Compare Webb's Images to Hubble

#179

Post by andai »

loxias wrote: post #150
mintyLemon wrote: post #62

Earlier quoted context omitted.

Link to that Hank Green video on YouTube: https://m.youtube.com/watch?v=Y7ieVkK-Cz0

The hero we need. Thanks!

These these two pages have some nice visualizations of the optical phenomena:

https://blogs.nasa.gov/webb/2022/02/03/photons-incoming-webb...

https://bigthink.com/starts-with-a-bang/james-webb-spikes/

Re: Compare Webb's Images to Hubble

#180

Post by ozzydave »

gcbirzan wrote: post #176
mtlmtlmtlmtl wrote: post #47

Earlier quoted context omitted.

IANA{astrophysicist, space engineer} but I do follow this closely and have what I call a working armchair understanding of this stuff. Anyone from relevant fields is welcome to gently correct any imprecisions. I always want to learn more and will thank you for it >could Hubble achieve the same quality of images as Webb if it was given 100x (or whatever) more time exposure? No, for a different and simpler reason: Hubb…

> This also will see much older light which is redshifted(the longer the travel, the greater the shift) out of Hubble's range of sensitivity. It's a matter of speed not distance, isn't it?

It’s both, but the contribution from distance will be much greater than from the relative speed for an old, distant galaxy.
Post reply on HN