Compare Webb's Images to Hubble
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Re: Compare Webb's Images to Hubble
#152What happens when it's pointed at Mars?
Ah found answer here
https://space.stackexchange.com/questions/57492/can-james-we...
Re: Compare Webb's Images to Hubble
#153Re: Compare Webb's Images to Hubble
#154Earlier 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.
Re: Compare Webb's Images to Hubble
#155Downvote me to hell, but as a person who has zero understanding of what differentiates Hubble from Webb, the pictures alone just aren't doing it for me. I was excited to see something completely new given 30 years and 10 billion dollars and instead I feel like I'm seeing what looks like an enterprise upgrade and feel slightly disappointed. What am I missing?
Based on my understanding of astronomy, the real research starts when scientists zoomed way in, thus the "enterprise upgrade" (increased resolution I assume?) is exactly what they're looking for.
Those published pictures are probably just for show (/to proof that the taxes you paid is have been used on a real project).
Re: Compare Webb's Images to Hubble
#156Here's a backyard telescope versus Webb: https://twitter.com/AJamesMcCarthy/status/154694183270093209... More comparisons on Twitter, some zoomed in: - https://twitter.com/Batsuto_/status/1546899241880240128 - https://twitter.com/Batsuto_/status/1546900387931766784 - https://twitter.com/JBWillcox/status/1546881033597075457 - https://twitter.com/jason4short/status/1546626672488632321 I'm not a physicist, so I've only…
Re: Compare Webb's Images to Hubble
#157Here's a backyard telescope versus Webb: https://twitter.com/AJamesMcCarthy/status/154694183270093209... More comparisons on Twitter, some zoomed in: - https://twitter.com/Batsuto_/status/1546899241880240128 - https://twitter.com/Batsuto_/status/1546900387931766784 - https://twitter.com/JBWillcox/status/1546881033597075457 - https://twitter.com/jason4short/status/1546626672488632321 I'm not a physicist, so I've only…
The spikes are caused by diffraction of light around the struts supporting the secondary mirror. Hubble has 4 supports for the secondary mirror. JWST has 3 support for the secondary mirror, which because...physics (I don't know I'm not an optics guy)...manifests as 6 diffraction lines. https://en.wikipedia.org/wiki/Diffraction_spike EDIT: It may be caused by both the diffraction spikes from the supports struts and th…
Re: Compare Webb's Images to Hubble
#158Earlier quoted context omitted.
Infrared is the only way to see things that are cold (as in not a star) or extremely far away (due to redshift).
What about reflected light, like most things we see in the solar system?
Re: Compare Webb's Images to Hubble
#159Downvote me to hell, but as a person who has zero understanding of what differentiates Hubble from Webb, the pictures alone just aren't doing it for me. I was excited to see something completely new given 30 years and 10 billion dollars and instead I feel like I'm seeing what looks like an enterprise upgrade and feel slightly disappointed. What am I missing?
Webb isn’t optimized to produce maximally pretty pictures, because most of Webb’s groundbreaking science is not necessarily going to involve pretty pictures. For example, Webb will tell us otherwise-unknowable things about the atmospheric composition of exoplanets—but it will not produce stunning photos of them (too small and far away to look like more than a pinpoint). Webb will tell us discipline-defining things ab…
To explain that concretely: Hubble was launched in 1990 and was fully functional once got its eyeglasses in 1993. But it wasn't until April 1995 that Jeff Hester was studying photo evaporation in the eagle nebula and motivated by studying the concentration of different molecular gasses, created a color image by mapping the narrow SII, Halpha, and OIII molecular lines filters to RGB (a false color image, called SHO or the 'Hubble pallet' by astrophotographers)-- creating the iconic "Pillars of Creation" image https://en.wikipedia.org/wiki/Pillars_of_Creation#/media/Fil... .
Hubble's large aperture and freedom from atmospheric distortion and light polution obviously contribute greatly to the image-- but much of the purely aesthetic beauty of the image, beyond the target, comes from the process and processing choices as illustrated by the many lovely images of the same object created by amateur astronomers whos processing follows in Dr. Hester's footsteps. E.g. https://www.astrobin.com/lglsd8/ https://www.astrobin.com/i1wffo Today, SHO images of many targets are produced by advanced amateurs with relatively inexpensive equipment, resulting in many breathtaking images of a sort that never existed before these techniques were popularized by the Hubble telescope. (random example: https://www.astrobin.com/fzp6u2 )
By the same token the JWT likely has locked inside it a tremendous potential for images which are both intellectually and aesthetically pleasing waiting to be unlocked through the skill and practice of people working with the data and their discovery of targets best matched to the instrument and those processing techniques.
Targets which are likely to be particularly aesthetically stimulating (as opposed to only intellectually stimulating) are also only a portion of what gets studied. A differential spectral measurement showing an oxygen atmosphere won't be much to look at-- but it will have a tremendous intellectual beauty.
Maybe in the future we'll see one of the billionaire space spacefarers partner up with some amateur astrophotographers to launch some modest equipment optimized for making aesthetic images (e.g. using optical designs that are free of diffraction spikes, like refractors or SCT reflectors). Who knows-- they might also make some interesting scientific discoveries because it's hard to study the aesthetic beauty of the universe without finding intellectual beauty of vice versa.
It might also be that processing techniques from JWT NIRcam images help terrestrial astrophotographers make better images. There are some reasonably large windows of NIR spectrum that we can image from earth-- e.g. J-band from 1170nm to 1330nm has good atmospheric transmission. And there is a lot in favor for terrestrial imaging in J-band: Light pollution is much less there, wavefront distortion from seeing is reduced, scattering (which follows the inverse 4th power of wavelength) is vastly lower. As a result you can even image the stars in the daytime with J-band. The big barrier is sensors because silicon sensors are blind past about 1100nm. The sensors used by JWT's NIRcam cost about $350k each and have to run at cryogenic temperatures. But sensor technology is improving (e.g. https://www.qhyccd.com/qhy990_qhy991/ QHY990 is more like $24k), and JWT might help drive along development by finding targets and processing techniques that could also be applied on earth just as happened with hubble SHO.