191–200 of 410 posts
Earlier quoted context omitted.
Existential dread pro-tip: The Wikipedia page on "Ultimate fate of the universe" is a fantastic way to compell the question of why anything ultimately matters. Coming up with personal answers to this is the ultimate character resolve exercise!
Nothing matters. You live for a while and then you die, but it sure can be a cool trip getting there!
Earlier quoted context omitted.
What would these look like, if you could point a ground telescope at the exact same spot? How much light is in the visible spectrum?
Here's a Hubble-based nebula that was imaged in both infrared and visible. https://esahubble.org/images/heic1406c/
Way to brighten my day with awe and wonder, way to ruin my day with existential dread about our place in the universe.
One of my favourite concepts from Douglas Adams was the Total Perspective Vortex, a form of punishment that would drive the victim insane by showing them the entire totality of existence and their place in it.
I've been interested in astronomy since I learned to read, and JWST has been planned for most of my life(all but 2 years if you count all explorations of ideas for a post-hubble telescope since about 95). I've been waiting for this my whole life, so this feels like a strangely personal event to me even though I had nothing to do with it myself. It's so hard to even put into words the tremendousness of this technological and scientific achievement, so I won't try.
Anyway, enough sap.
I'm super stoked that they've already started taking spectra of exoplanets. This one was sort of an "easier" one but the detail was unprecedented as with all the other observations. I can't wait to see some results on some of these smaller rocky planets in their star's "goldilocks zone".
These are the planets that have simply been out of reach until now, and are the most interesting in terms of searching for signs of life.
Earlier quoted context omitted.
The difference between 'actual science' and 'some touched up version of objects in our universe' is smaller than you might think: no matter how good your eyes, if there was no frequency shift involved you would not be able to perceive the image, other than as an array of numbers. To facilitate your consumption of the data it has to be frequency shifted and the easiest way to do this is to map the IR intensity to a ra…
Thanks, but how is the sausage made then? Guess, that’s my main question. I get that the aquired data needs to be transformed in a way so we get an image that depicts a reality we can visually process. I honestly thought there’s some tools in Nasa’s imaging group that, based on scientific rules, pumps out an image that is correct - seeing Photoshop in use left me wonder… I get that the investment needs to be “sold” t…
I can't tell you because I wasn't looking over the shoulder of whoever made the image, but at a guess they started off from a black and white image, then turned it into an RGB image and change the various hues until relevant details became easier to see. The reason that that works is because a large scale structure has areas that emit at roughly the same intensity so you can bring these out by colorizing such a range with a gradient around a single hue.
This is not an automated process because a computer would not know what we humans find 'interesting structures', if you could put that into some form of definition then you might be able to automate the process in the same way that black-and-white images are automatically colorized (which works, but which is sometimes hilariously wrong).
As for the sausage, how it is made is interesting, how it tastes is from a PR perspective probably more interesting. And regardless you could argue that anything that differs from an utterly black square is 'not truthful'.
Earlier quoted context omitted.
Gravitational lensing. From the description[0]: Other features include the prominent arcs in this field. The powerful gravitational field of a galaxy cluster can bend the light rays from more distant galaxies behind it, just as a magnifying glass bends and warps images. Stars are also captured with prominent diffraction spikes, as they appear brighter at shorter wavelengths. [0] https://webbtelescope.org/contents/new…
Will the JWST be able to make photos of black holes, similar to the ones the EHT made? And if yes, can the JWST be used to study black holes?
The EHT images are created using synthetic aperture techniques to create an effective aperture with a diameter of earth's orbit around the sun. But this is only currently possible at radio frequencies due to our ability to capture, store, and coherently combine the phase information. It's essentially SDR beam forming across space and time.
We can also study black holes though visible and IR observations through their effects of the things around them-- lensing from their mass, matter heated up by falling in. Here is an image I took of the relativistic speed matter jet believed to originate from black hole in M87: https://nt4tn.net/astro/#M87jet ... and Webb can do a lot better than I can with a camera lens in my back yard. :)
Aside, there is some controversy about the EHT black hole images. A recent paper claims to be able to reproduce the ring like images using the EHT's imaging process and a simulated point source-- raising the question of the entire image just being a processing artifact. https://telescoper.wordpress.com/2022/05/13/m87-ring-or-arte... Though it's not surprising to see concerns raised around cutting edge signal processing-- LIGO suffered from a bit of that, for example, but confidence there has been improved by a significant number of confirming observations (including optical confirmations of ligo events).
Earlier quoted context omitted.
I fear there won't be any more JWSTs at all. People are already bitching about how much it cost and that all it does is make pretty pictures right here in this thread and there were many times that it came within a hair of having its budget slashed. Super happy we have one JWST, and I hope fervently that it will outlast its original mission by a large fraction, every sign right now points in that direction.
> People are already bitching about how much it cost I like to point out that Microsoft could have paid for seven JWSTs (development costs and all) with what they paid for one Activision.
Not to spoil anything, but anybody else here finding these results quite underwelming?
Things like looking for IR spectra of water vapor in the atmosphere of planets outside of our solar system we can't even do from earth, since our own atmosphere is not transparent at those wavelengths due to the water in it. (ditto for oxygen).
A thing they mentioned in the presentation today but mostly only in passing, was that images like that deep field image were captured with only something like a dozen hours of data collection and had better resolution and much better SNR and many more far redshift objects visible at all than an image of the same scene that took Hubble weeks of data collection to make.
I remember reading something in the lines of: we know this nebula to be composed of gasses X and Y, which have colors A and B. As a layman it was unclear to me if this statement means they are applying a color palette to a monochrome image(s) using some educated guesses or something else. Is infrared the only (or the most convenient, most useful etc) spectrum visible given the great distance? If we could get close en…
As you may be aware, all digital images are composed of a color palette applied to monochrome images, it just so happens that we usually pick a color palette of red, green, and blue, which ideally correspond as closely as possible to the three wavelengths of light to which the imaging sensors in our cameras (and also our eyes) are sensitive, thus reproducing what our eyes would see in person.
In the case of JWST, mid- and far-infrared sensors were chosen for several reasons, the first being that due to the accelerating expansion of the universe, light from further away (equivalently, light from further back in time) has been stretched out along its path of travel, causing its wavelength to be shifted further into the infrared spectrum. Another possible reason is that infrared wavelengths penetrate the interstellar dust clouds much better than visible or ultraviolet light, allowing us to see stars and galaxies that were previously hidden by dust.
Since JWST captures wavelengths of light that we can't see, we have to apply some sort of visible-light palette to the monochrome images it sends back. At the bottom of this image, you can see which wavelengths were mapped to which visible-light colors: https://stsci-opo.org/STScI-01G7N9A6934R1WRWBJY1ZXB98B.png One key aspect of this mapping is that the order of wavelengths has been preserved; shorter IR wavelengths are colored blue while longer ones are colored red. It's likely that this mapping is non-linear though, so the relative distances between IR wavelengths are not the same as the distances between the hues in the image, and this mapping was chosen to maximize the visible detail in the resulting image, as well as to highlight scientifically relevant information such as dust clouds and areas of star formation, so it's not totally arbitrary.
In addition, the dynamic range of JWST is much much larger than the pixels in any display. The raw data values probably range from 0 to some hundreds of thousands, while your display's pixel brightness can only go from 0 to 255 (or maybe 1023, if you have a 10-bit HDR display). While we could simply map the maximum pixel value to 255 and compress everything else in between, this would lose nearly all of the detail present in the darker regions of the images, compressing them to 0. Instead, a non-linear brightness mapping is applied, to best represent all the information present in darker regions without blowing out the bright stars and galaxies.
So to answer your questions, the colors shown in the images are not what you would see in person. Without any enhancements you probably wouldn't be able to see much if any of the dust clouds, and many of the redder galaxies would not be visible to you at all, while all the rest would be different hues than the ones shown (probably mostly whites, yellows, and reds).
