Show HN: A JWST/Hubble deepfield comparison on a zoomable/pannable map interface
academo.orgJWST and Hubble have roughly similar angular resolution. Hubble marginally better. JWST needs larger mirror for the same angular resolution because it uses longer wavelengths.
Hubble: 0.04 arcsec at 500 nm
JWST: 0.068 arcsec at 2 μm
(If I remember correctly JWST took this image in less than 12 hours, Hubble stared at it for much longer. Correct me if I'm wrong).
Hubble's composite of SMACS took 5 orbits, which ends up being about a couple hours maximum. Most websites talked about the deep fields such as XDF (hundreds of orbits) while showing the comparison between the RELICS and JWST pictures, which I believe was very misleading from how this is repeated. Not to detract from its capabilities, of course.
Would JWST have made a more detailed picture if it had stared on that spot as long as Hubble did?
Resolution would not improve, but contrast would and you would be able to see fainter objects with less noise.
The longer you "expose" the more detail is revealed yes.
As an aside, does anyone on HN know why one telescope’s name includes a first name and the other doesn’t.
We don’t call the first telescope the Edwin Hubble Space Telescope
I think it's because they are two syllables. After a short time objects named after people* (Carnegie Mellon, FDR Drive etc) tend to lose the association with the person so honored and just become strings. This is doubly so for names of international scope.
Think of Google, Facebook, Netflix, Workday, Coinbase: two syllables, each name an iamb (which is especially effective in English). Sure, there are numerous counterexamples (microsoft, Amazon), but generally the corners get knocked off and even turn into acronyms in public usage (GM, GE).
Single syllables are too short for infrequently used words (this appears to be true for any language) -- you don't want to waste a lot of time saying "am" since you say it a lot; when you say "biceps" you want enough variability that your brain has time to parse it.
Webb is a much more common surname than Hubble.
This isn't a real image of an exoplanet right? The one in the background. Nowhere does it say that, which I think is beyond the ability of even JWST, to resolve an exoplanet at 50 light years?
https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-...
The image in the background is an artist's rendition. The graph is the real image.
Exoplanets are too far away and too small to image directly.
> Exoplanets are too far away and too small to image directly.
If you mean resolving details of the exoplanet, then yes that is currently true. But we have imaged exoplanets directly, meaning taken an image of a star where one can also see the planet directly in the image. [0] has a list of directly imaged exoplanets.
[0] https://en.wikipedia.org/wiki/List_of_directly_imaged_exopla...
Woah didn't know about that. The gif on that page is incredible!
It's an impressive technique. Direct imaging finds planets that would be unlikely to be identified via other detection techniques (such as measuring the wobble in the parent star's radial velocity or measuring photometric eclipses as the planet passes between us and the parent star).
I do hope they can train the JWST at a close-by star and at least see a dot that represents an exoplanet.
These are annoying to me because lacks of real difference from a senior astronaut viewpoint. As a normal user, the only difference i could see is just "brighter", anything more to add to the details ?
Else i could say, just the same.
JWST shows a much bigger part of the wavelength spectrum. That means it can image things that would just not show up in Hubble.
E.g. think about far away galaxies that have been redshifted so much (due to the expanding universe) that they fell below the lower wavelength threshold of Hubble.
Yes, also cooler objects show up, which are otherwise invisible and you can see through interstellar dust and clouds better.
Zoom in on a small section of sky and toggle between James and Hubble. James reveals many additional galaxy in each tiny slice of image. Probably hundreds or more in that one image alone.
Check out the video by Scott Manley, he explains quite a bit: https://www.youtube.com/watch?v=0FWO1Pvbhq4
Check out some of the reddest galaxies in the Webb image. Even the big ones are entirely invisible on the Hubble image.
Would there be a moment we cannot zoom in further because we hit the event horizon with the jwst? Or are there still hidden galaxies behind what we can see with the jwst?
I think it won't be a hard border per se, but it'll just turn into extremely redshifted noise at some point; beyond infrared you end up in microwaves, which leads to the cosmic microwave background radiation: https://en.wikipedia.org/wiki/Cosmic_microwave_background
The furthest back potentially visible stuff before the dark age won’t be galaxies, which formed after the first stars. We still have never seen a first generation star, and I’d be surprised if Webb could.
I want to see a comparison of the infrared from Hubble vs the infrared from James.
I also want to normalize calling JWST just "James" :)
The Hubble only went into very near infrared, nothing like JWST. Also JWST is a million miles from earth so it is ultra cold.
I like "James Webb Science Telescope" for JWST.
Just Wonderful Space Telescope
Nice. It would be good to have a way to reset to get back to the initial state after zooming/panning.
I love that there is a star showing some drift
There's no drifting there. What you are seeing is gravitational lensing. The light of (most likely a galaxy) is bent around another galaxy or star which distorts its appearance. Also this means it can potentially show up multiple times on the image (e.g. opposite side w.r.t. the lensing object)
Thanks for the comments! It does look like some stars may be exhibiting stellar drift, I've isolated an example here: https://academo.org/demos/james-webb-vs-hubble-telescope-com... This is from the middle-right side of the deep field. If you look slightly below the two central galaxies, there is what looks to be a foreground star (I say that due to its brightness and the fact it has a starburst effect) and between the two frames, there seems to be a noticeable shift in position that doesn't occur with other objects.
Yeap, this is very likely proper motion. That star is in our galaxy.
I was wondering how you made that gif and looking for an option on the UI to automatically export one, but then I realized you are OP. That would be a cool feature to add.
It might also be caused by parallax. The image might have been taken at different points in the Earth's orbit around the sun.
That's a really good point. I think there's a high chance that the photos were taken from quite different locations because Hubble orbits the earth at 570km, whereas JWST is actually at the L2 Lagrangian point, which is about 1.5 million km away from Earth.
Fair enough, I misinterpreted GPs post. He and you are obviously correct.
This is incredible. Thanks for sharing it!