221–230 of 254 posts
Does someone have any intuitive explanation on why Hubble images for bright stars seem to have a cross-shaped lens-flare effect, while for JWT it's got six spikes? It might be because of a different post-processing algorithm, or some phi-related magic, just curious a bit.
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I think this is a little harsh, but I actually generally agree. I'm a total laymen here and my PRIMARY TAKEAWAY has been the IR component and how much more and further away you can see because of it.
I get what you are trying to say here, but someone posting on HN about "the IR component" using the nom de guerre "Enginerrd" might not be "a total laymen" :-)
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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!
Newtonian physics does have the Doppler effect which can cause red shift, but it doesn't accurately explain the red shift that occurs when observing distant galaxies. That's because this red shift occurs due to three factors: 1) The galaxy is moving away from us. This is most like the classic Doppler effect, but because of the high relative velocities involved, time dilation needs to be taken into account to model th…
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According to the Wikipedia definition, I'd say that Webb's artifacts could be classified as "lens flares". >This happens through light scattered by the imaging mechanism itself, for example through internal reflection and forward scatter from material imperfections in the lens. Lenses with large numbers of elements such as zooms tend to have more lens flare, as they contain a relatively large number of interfaces at…
Diffraction spikes are caused before the lens gets involved; improving the lenses cannot remove the spikes (though there may be structures causing diffraction spikes in-between lenses). The spikes from JWST are primarily caused by the edges of the mirrors and the three support struts. There likely is some amount of lens flare (though I don't know if it is significant, the optics are Very Good), but the dominant artef…
That sounds to me like "light scattered by the imaging mechanism".
Does someone have any intuitive explanation on why Hubble images for bright stars seem to have a cross-shaped lens-flare effect, while for JWT it's got six spikes? It might be because of a different post-processing algorithm, or some phi-related magic, just curious a bit.
I believe the six spikes from JWST are because of its hexagonal mirror segments.
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I believe the six spikes from JWST are because of its hexagonal mirror segments.
This was my guess as well, but if it's correct, I don't understand why the Hubble images show 4 spikes. I thought Hubble's main mirror was circular, not a square.
https://en.wikipedia.org/wiki/Diffraction_spike
>"...four spider vanes supporting the secondary mirror. These cause the four spike diffraction pattern commonly seen in astronomical images."
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…
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?
Everyone in “big science” remembers the cautionary tale of the Superconducting Super Collider, which was cancelled mid-project when it became politically viable to oppose it as a waste of money. The circular tunnel is still sitting dusty and abandoned down in Texas while CERN runs another round on the LHC.
Big results that gather public praise go a long way toward making sure the next big science project will at least be seriously considered.
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Hey, that's an interesting and uncommon question that I had not seen elsewhere -- They did not release or talk in much technical detail of how the images were assembled, which I'm sure will be done at some point. I do not think the colors do correspond (at least not deliberately), for 2 reasons: First is that the image of the Deep Field ("SMACS") contains galaxies at a range of redshifts. For example there may be gal…
Thanks for the write-up! It's definitely important to mention the single-channel aspect of the sensors because I guess many people probably don't understand that.
This kind of mimics the human eye, which is sensitive to those three approximate color frequencies, but it's interesting to note other species besides humans (and, apparently, even some humans)[1] have vision that work with more "filters", or on different spectra (such as honeybees).
I've always found it kind of amazing that so many satellite imaging devices work on far greater spectral ranges with far more color filters, being able to discern far more information than we could with the naked eye (but in essentially the same way).
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Also, when comparing the deep field images I don't think it can be stressed enough the difference in exposure time between HST and JWST images (Hubble had a 10x longer exposure time). Many many more distant galaxies would become visible in the JWST image with the much longer exposure time. I look forward to seeing some long-exposure deep field images from JWST!
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.
Will there be thousands of additional extremely red shifted galaxies?