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James Webb first images – complete set of high resolution shots now live

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Re: James Webb first images – complete set of high resolution shots now live

#331

Post by jvanderbot »

ehsankia wrote: post #311
jvanderbot wrote: post #304

Earlier quoted context omitted.

Maybe my question would be better asked for other objects images then, but I can just google how far things are redshifted at extreme distances as well.

My understanding is that the IR here is used to see "through" the "smoke", so you can see more details that would normally be obstructed. A good way to see this is comparing it to Hubble [1], a lot of the extra detail you see is thanks to IR letting you see the stars behind. [1] https://johnedchristensen.github.io/WebbCompare/

Understood!

What I was asking is: Is the target's normally-visible light redshifted into the same bands that JWST is measuring, higher? or lower frequency?

That doesn't have anything to do with why JWST uses IR.

Re: James Webb first images – complete set of high resolution shots now live

#332

Post by BurningFrog »

jcims wrote: post #263
oAlbe wrote: post #229

Earlier quoted context omitted.

Is there a way to rapport an arcmin to a measurement that would be more easily understandable? Not necessarily as a multiple of grains of rice.

Your thumb at arms length is ~2 degrees or ~120 arcminutes wide. The fingernail on your index finger at arm's length is ~1 degree or 60 arcminutes wide. The moon is about half a degree or 30 arcminutes wide. This doesn't make sense but give it a try tonight if the moon is out. FWIW many of the galaxies and nebula you see in astrophotography are actually bigger in the night sky than one might guess. Andromeda for exam…

I propose we use Moon Diameters (MD) as the official HN unit for sky distance.

Re: James Webb first images – complete set of high resolution shots now live

#333

Post by checkyoursudo »

silvi9 wrote: post #142
idiotsecant wrote: post #65

Earlier quoted context omitted.

Nothing matters. You live for a while and then you die, but it sure can be a cool trip getting there!

You think nothing matters? How can you be so sure?

I'm not sure that matters, does it?

Re: James Webb first images – complete set of high resolution shots now live

#334

Post by yread »

clint wrote: post #165
yread wrote: post #149

Earlier quoted context omitted.

I would have expected ImageJ has plugins better suited to work on science

Why would you assume this?

I work in microscopy and everyone uses it. Precise work with LUTs, images with z-,c- and t- dimensions, image formats, api, ...

Re: James Webb first images – complete set of high resolution shots now live

#335

Post by BurningFrog »

j0e1 wrote: post #234
chaps wrote: post #64

Direct links -- Stephan's Quintet (NIRCam and MIRI Composite Image): https://stsci-opo.org/STScI-01G7DB1FHPMJCCY59CQGZC1YJQ.png Southern Ring Nebula (NIRCam and MIRI Images Side by Side): https://stsci-opo.org/STScI-01G79R28V7S4AXDN8NG5QCPGE3.png “Cosmic Cliffs” in the Carina Nebula (NIRCam Image): https://stsci-opo.org/STScI-01G7ETPF7DVBJAC42JR5N6EQRH.png Webb's First Deep Field (NIRCam Image): https://stsci-opo.org…

> “Cosmic Cliffs” in the Carina Nebula (NIRCam Image): > https://stsci-opo.org/STScI-01G7ETPF7DVBJAC42JR5N6EQRH.png Is this for real?! It looks like it came right out of a Sci-Fi movie/book. Could anyone explain how much of this is post-editing magic?

Much of it is in infrared light we can't see, so it's "transposed" to the visible spectrum.

Not much weirder than looking at an X-ray image.

Re: James Webb first images – complete set of high resolution shots now live

#336

Post by s1artibartfast »

jacquesm wrote: post #321
s1artibartfast wrote: post #317

Earlier quoted context omitted.

You are obviously missing the point. They want to know what it would look like to a human observer.

It's the wrong question to ask because a 'human observer' would see absolutely nothing. The age of the objects you are looking at is such that you are looking into the past not at something the is still there in the present, so if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed. At this level 'distance' = 'time'.

This isn't true at all, many of the objects are not far away.

The Carina Nebula (imaged) is 7,500 light years away. It is still there.

It seems like people are going through mental gymnastics to avoid answering the question. If someone asked what a famous black and white photo like raising the flag would look like in person, would people give the same nonsense answers? e.g. "There is no "in real life", "the past cant be seen"

For the Carina Nebula[2] :

"Several filters were used to sample narrow and broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Red: F444W, Orange: F335M, Yellow: F470N, Green: F200W, Cyan: F187N, Blue: F090W"

This is in comparison to the human eye, which sees 630 nm for red, 532 nm for green, and 465 nm for blue light.

That is not to say the Nebula isn't also observable in visible light, you would just be seeing different colors and perhaps features. probably something like this visible spectrum imagine of a different part of the nebula

For the other images, what you would see in person ranges from very similar to nothing depending on the image, and pixel in the image.

[1] https://en.wikipedia.org/wiki/Raising_the_Flag_on_Iwo_Jima

[2] https://webbtelescope.org/contents/media/images/2022/031/01G...

[3] https://esahubble.org/images/heic0910e/

Re: James Webb first images – complete set of high resolution shots now live

#337

Post by Dopameaner »

I didnt realize we had a 3d map of dark matter. Something to be mindful of now.

Gathered the summary from the Royal Observatory’s website[1] regarding Hubble's major contributions

" - Helped pin down the age for the universe now known to be 13.8 billion years, roughly three times the age of Earth.

- Discovered two moons of Pluto, Nix and Hydra.

- Helped determine the rate at which the universe is expanding.

- Discovered that nearly every major galaxy is anchored by a black hole at the centre.

- Created a 3-D map of dark matter."

Re: James Webb first images – complete set of high resolution shots now live

#338

Post by yaakov34 »

randyrand wrote: post #291
j0e1 wrote: post #234

Earlier quoted context omitted.

> “Cosmic Cliffs” in the Carina Nebula (NIRCam Image): > https://stsci-opo.org/STScI-01G7ETPF7DVBJAC42JR5N6EQRH.png Is this for real?! It looks like it came right out of a Sci-Fi movie/book. Could anyone explain how much of this is post-editing magic?

Does anyone have a simulated image of what it would look like in visible light without red shifting? i.e. If we were moving at the same velocity of the Nebula looking with our own eyes. i.e. What it would look like "in real life if I actually went there"

These objects are much too faint to see much of anything with human eyes. We can see them in astrophotography because the exposures are hours long (or weeks even, sometimes), and because telescopes gather more light than the eye per unit time, as well. This is why these nebulae look like billowing clouds - they are huge (light years across), so some light is absorbed as it crosses them, and some of the infrared light emitted by them adds up. And then we enhance the effect by taking very long exposures. If we actually went and stood near or even inside these nebulae, we would still be in pretty hard interstellar vacuum, and we wouldn't see anything.

Re: James Webb first images – complete set of high resolution shots now live

#339

Post by sbierwagen »

jvanderbot wrote: post #331
ehsankia wrote: post #311

Earlier quoted context omitted.

My understanding is that the IR here is used to see "through" the "smoke", so you can see more details that would normally be obstructed. A good way to see this is comparing it to Hubble [1], a lot of the extra detail you see is thanks to IR letting you see the stars behind. [1] https://johnedchristensen.github.io/WebbCompare/

Understood! What I was asking is: Is the target's normally-visible light redshifted into the same bands that JWST is measuring, higher? or lower frequency? That doesn't have anything to do with why JWST uses IR.

Redshift refers to how the wavelength of a photon can change if the observer is moving relative to it, (Doppler shift, redshift if you're moving away from the photon, blueshift if you're moving towards it) or cosmological redshift. (The fabric of the universe expanding, reducing photon energy)

NGC3372 is a cloud of (relatively) hot gas and dust. It's emitting broad spectrum blackbody radiation: it's emitting on all wavelengths. You can look at the same cloud at different wavelengths and see different things, telling you what parts of the cloud are at what temperature, or relative chemical composition, or what parts are ionized: http://legacy.spitzer.caltech.edu/uploaded_files/graphics/fu... Nothing here is redshifted, Spitzer is just capturing different light entirely.

In the side by side of JWST and Hubble https://pbs.twimg.com/media/FXecm6vXwAMPhoc?format=jpg&name=... https://pbs.twimg.com/media/FXecnp2XkAE4Rs5?format=jpg&name=... you see broadly the same thing, but Hubble is almost all visible-light while JWST goes deeper into infrared and sees cloud structure that Hubble doesn't.

Re: James Webb first images – complete set of high resolution shots now live

#340

Post by JacobThreeThree »

jacquesm wrote: post #321
s1artibartfast wrote: post #317

Earlier quoted context omitted.

You are obviously missing the point. They want to know what it would look like to a human observer.

It's the wrong question to ask because a 'human observer' would see absolutely nothing. The age of the objects you are looking at is such that you are looking into the past not at something the is still there in the present, so if we were to transport you there you would not recognize the various objects in visible light at all, too much time has passed. At this level 'distance' = 'time'.

>a 'human observer' would see absolutely nothing

Although the accuracy of infrared, or other non-visible spectrum digital representations, could be disputed you would definitely see something similar in visible spectrum as compared to infrared, but with much more dust. Most objects that are emitting energy are doing so in many portions of the spectrum.

See this example: https://esahubble.org/images/heic1406c/

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