The post-processing in the webb images is hilarious. Marketing at its best.
Compare Webb's Images to Hubble
231–240 of 254 posts
Re: Compare Webb's Images to Hubble
#232Earlier quoted context omitted.
OP clearly means from an observer moving at (approximately) the same velocity as the object emitting the light.
The objects aren’t really moving in that sense. The expansion of space over time is what stretches the light.
Without a fixed point of reference, what is the difference?
Re: Compare Webb's Images to Hubble
#233Strange, when I compare the two images of Stephan's Quintet [1], it appears much more "progressed" in the new WEBB image [2]. But that should be impossible. [1]: https://en.wikipedia.org/wiki/File:Stephan%27s_Quintet_Hubbl... [2]: https://johnedchristensen.github.io/WebbCompare/img/Stephans...
Overlaying them, it seems the JWST images have brighter galaxy edges and gas. This makes the galaxies look bigger, which in turn could make it appear as if the galaxies are closer together. Is that what you mean with 'progressed'?
Yes, I think you're right - also, the linked HUBBLE image from wikipedia is rotated a bit, which increases the effect that two of the 5 galaxies appear to be closer together in the WEBB image.
Re: Compare Webb's Images to Hubble
#234Earlier quoted context omitted.
The objects aren’t really moving in that sense. The expansion of space over time is what stretches the light.
Without a fixed point of reference, what is the difference?
The difference is the expansion of space is accelerating over time. And certain wavelengths of light will be blocked by gas in the intervening space, and which light is blocked changes over time based on how red-shifted it is. Special Relativity isn't enough to explain this.
Re: Compare Webb's Images to Hubble
#235Re: Compare Webb's Images to Hubble
#236I'm slightly surprised they haven't gotten rid of the stellated hexagon artifacts with software.
And replace them with what?
Nothing, that's kinda the point.
I'm not talking about just deleting the pixels. If you know your measurement instrument introduces artifacts, you just move it around or use some ground-truth image until you map the artifacts and then subtract them out by convolution.
Re: Compare Webb's Images to Hubble
#237Earlier quoted context omitted.
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!
Yeah, you’re correct, you don’t need to invoke relativity to explain the Doppler effect. Sibling comment did a good job explaining the ways relativity does impact redshift, but my initial statement (“because of relativity…”) was not correct.
Re: Compare Webb's Images to Hubble
#238For 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…
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?
> 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.
Re: Compare Webb's Images to Hubble
#239I'm actually most looking forward to seeing a picture of our planets. I wonder what kind of resolution we'll get of Jupiter and Mars in particular. Also curious about what the closest stars to our solar system would look like. Of course it also makes me wonder what would we be able to see given a 100x increase in aperture. Like for example if we could send up something extremely large on Starship. Would we be able to…
We've got very good pictures of our own planets thanks to probes that did flybys. Maybe I'm way off but I'm pretty sure JWST won't be able to beat those. I also wonder if it can even handle that much light, I know it can't look at the moon or it will burn out.
Oh for sure it won't. I'm more interested in that as a tech demo.
Re: Compare Webb's Images to Hubble
#240Earlier quoted context omitted.
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.
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?
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.