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Comment by ehsankia | Hacker News Reader

Wow, you can really see the gravitational lensing on that one.

I was wondering which of the 5 photos [1] they'd tease today (remaining 4 are coming tomorrow). My guess was also gonna be the deep field one, especially since it maps nicely to the well known Hubble photo. But now it begs the question, how does this one compare to the Hubble one in terms of scale/angle.

[1] https://petapixel.com/2022/07/08/nasa-shares-the-5-cosmic-ta...

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According to the Webb Space Telescope post [1]: "This slice of the vast universe is approximately the size of a grain of sand held at arm’s length by someone on the ground."

According to the Hubble Site post [2]: "...the Hubble Deep Field image covers a speck of the sky only about the width of a dime 75 feet away"

Edit: So that same page for the Webb image states 2.4 arcmin across, compared to ~3.4 arcmin for the Hubble Ultra Deep Field image [3]

[1] https://webbtelescope.org/contents/media/images/2022/038/01G...

[2] https://hubblesite.org/contents/news-releases/1996/news-1996...

[3] http://curious.astro.cornell.edu/about-us/98-the-universe/ga...

Yea, feels like the swirly bokeh of a photo taken using a lens with mechanical vignetting or sagittal astigmatism (colloquially Petzval, but field curvature is both sagittal and tangential).

(like https://commons.wikimedia.org/wiki/File:16042014_Bokeh.jpg, https://photo.stackexchange.com/questions/52126)

Is the lensing the result of a single large galaxy in the middle that is “closer” or many galaxies?

According to https://www.newscientist.com/article/2328132-james-webb-spac..., "This first image is a region of space called SMACS 0723, which contains what astronomers call a gravitational lens. In areas like this, a massive object relatively close to Earth behaves like a magnifying glass, distorting space and stretching the light of anything behind it." and "The gravitational lens in SMACS 0723 is particularly strong because the nearby object distorting space-time is not one galaxy, but a large cluster of galaxies."

So where are those galaxies? Are they not visible in infrared? Or has light bent so much that those galaxies are not visible?

From the analysis I've seen, I understand the white-appearing objects at the center of the image are the galaxies that compose that galaxy cluster. The very red and deformed galaxies around them are much further away but made visible due to the gravitational lensing.

Some of those arcs seem concentric, so I would assume a mass in that direction. More likely there are multiple masses distorting multiple objects into multiple arcs, but I am not an astronomer and my guess is as good as anyone else's (who's not an astronomer)

From the link in ops post:

“The combined mass of this galaxy cluster acts as a gravitational lens, magnifying much more distant galaxies behind it.”

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