NASA's Webb depicts structure in 19 nearby spiral galaxies | Hacker News Reader

NASA's Webb depicts structure in 19 nearby spiral galaxies

webbtelescope.org

97 pointsFergusArgyll34 comments

I saw the title and thought it was Markarian's Chain (not to be confused with Markov's Chain) but it's not.

I thought I'd share this picture I took of 19 galaxies rising over Mt. Lassen with a 500mm lens. It is stacked and tracked (separately for ground and sky) but the composition is unaltered. Many of these galaxies are 1/4 to 1/2 the size of a full moon, just too dim to see with the naked eye.

https://dheera.net/photos/calnight/#&gid=1&pid=15

That is brilliant, thank you so much for sharing. The galaxies’ enormous size is truly jaw dropping. I had absolutely no idea they were this large, in the night sky.

Have you ever seen them live, though an image intensifier / night vision system? I feel there would be something profound about seeing a galaxy with my own (albeit enhanced) eyes.

I don't have a night vision system so haven't tried that on Markarian's chain. What is much easier for naked eye vision is the Andromeda galaxy, which is much closer. It is actually about 6 times the visual size of a full moon in the sky, though with naked eye in a dark enough place you can barely see the fuzzy blob of a core with off-center vision. You can see the core more clearly with binoculars. However it will look small because you are only looking at the core. The magnificant spiral arms are what extend around that core 6 times the size of a moon. You can easily see the spiral structure with a consumer full frame camera. A star tracker will produce a crystal clear image of it, but without a tracker, a short exposure and high ISO can still show its existence. Even a 50mm or 100mm lens is enough to make it out. At 500mm it will fill the whole frame almost corner-to-corner. It's huge.

Keep in mind galaxies are extremely low density on average. So even though Andromeda has about 1 trillion stars, it's still mostly vacuum with lightyears of distance between adjacent stars inside it. So it appears much, much, much dimmer than the individual stars in the sky from our own galaxy.

The only time I've seen things is from using one of Sony's mirrorless cameras with ultra high ISO while attached directly to a telescope. Things that would normally take long exposures were visible in realtime. I haven't tried using that with a wide angle lens. Would be interesting thing to try

I am lucky enough to live in a place that I can see the night sky as it should be. It takes time to be able ‘see’ the Milky Way. And what made it easy to understand was seeing andromeda through binoculars.

Realising that if I was in andromeda looking back at the Milky Way it would look the same. I could then understand that I wasn’t looking at the Milky Way, but part of it and looking out.

Really grounded me.

Wow, that's superb. It really helps me try to visualise the size they appear in the sky. Obviously I still can't truly wrap my head around the scale of everything, but it's a start.

For anyone who hasn't seen it yet, this video by Epic Spaceman is a treat if you want to try to visualise just how big our own galaxy is: https://youtu.be/VsRmyY3Db1Y?si=I7y5bL_9qV_lazPQ

This is a nice composite (not mine) showing the relative sizes of various deep sky objects:

https://www.reddit.com/r/astrophotography/comments/19do9iu/c...

Very impressive.

Very impressive. Thanks for sharing! I just found a couple of new desktop backgrounds.

I find the unity of structures here quite re-assuring. It tends to say that large spinning masses of largely undifferentiated neutrons (or whatever) become structures which reflect both their spin, and gravity, and how the neutron stew decays as it cools.

If there was only one, I'd be surprised. If we see many of more detailed forms but they tend to a common pattern, "thats physics"

It's mostly protons not neutrons.

It's mostly dark matter. Apparently galaxies wouldn't be able to hold those shapes if they were merely made of the dust, gas, and stars we can see.

I always thought that frame-dragging, or something similar, could account for this, but I assume it's been ruled out already.

There is some debate regarding gravitational self-interaction. This[1] post gives an overview of a proposal by Deur.

Note though that while this is peer-reviwed work, it's still contentious.

[1]: https://astrobites.org/2020/08/17/the-alternative-to-dark-ma...

The only thing "dark matter" and "dark energy" have going for them is unfalsifiability for our type 0.5 civilization. Keep in mind that general relativity isn't actually even fully worked out for real systems.

> The only thing "dark matter" and "dark energy" have going for them is unfalsifiability for our type 0.5 civilization.

I don't think that's fair at all. Neither phenomenon is unfalsifiable.

By definition, dark matter an unknown gravitational effect. It's not fundamentally unfalsifiable, we just don't know what's causing it. The assumption is difficult-to-detect matter seems most likely because theories like MOND which suggest that "maybe gravity works differently from how we thought" are being investigated actively and just don't seem very likely so far.

Every time I dive into the virtual endlessness of deep space, I feel so blessed knowing we’re part of something beautiful. Cold. Brutal. Terrifying. Not even a pale blue dot, just a nothing but still something.

> I feel so blessed

> Cold. Brutal. Terrifying.

Are you sure? Haha.

Of course not, we all know it’s CGI upon a flat earth ;-)

They have a darn hard case, can’t argue with that, can I?

Immediately set as my laptop background

If you’ve got a Mac you can set it up as a live wallpaper and have it scroll across the image over the course of the day. I’m sure there’s a better way to do it but this is how I’ve done it with other Webb images in the past.

https://github.com/trescenzi/dynamic_wallpapers

Not the same but all galaxies billions of light years are part bare many similarities. I fathom the way things seem to mirror each other in the universe, civilizations will also be similar to our own. Given they all have exact rules of physics and math.

Or they are seeded by the same people. Yeah, I recently re-watched Stargate.

As far as the exact rules of physics, we're built for 1G. We keep finding Super Earths where gravity would be more than 1G. How would those same physics and math work out for civilizations?

That's just because our current way of finding exoplanets works best with heavier planets. There could be billions of earth-like planets but we can't (yet) find them effectively.

Does anyone have an estimation if the amount of pixels if james web would make a full 360 degree image?

It probably depends a lot on the instruments and processing used. This deep field image from a while back

https://webbtelescope.org/contents/media/images/2022/035/01G...

Is about 4.5k pixels(as published)/0.04 degrees (2.4 arcmin) a side so 360 degrees of that would be an image with 40 million pixel sides unless I fatfingered something in calculator.

There are a few issues that cross my mind ...

First I assume you mean a '360 x 360 degree' image - meaning you don't want a circle, but a sphere. [0]

Second, much of your image would not be useful, obstructed by the Sun, Moon, Earth, and all that direct and reflected sunlight. I suppose JWST, being in L2, follows the Earth's orbit around the Sun. Over a year, does L2 allow a clear view of the entire celestial sphere?

Third, the number of pixels would seem to depend very much on the chosen depth of focus. I don't know what the zoom levels are, but theoretically it could snap a nice, sharp wide-angle shot of the entire unobstructed sky. (I don't think wide angle is really JWST's mission - more high zoom to spots over 13 billion light years away, but I also don't know much about its optics.)

[0] What is the proper mathematical expression instead of the awkward '360x360 degrees'? what do astronomers and airplane pilots use? I can't think of one atm, but there must be one? A spherical coordinate system for direction, analogous to degrees of a circle?

The "area" in a spherical coordinate system is cold "solid angle" with unit steradian.

The whole sky has 4pi steradian.

https://en.m.wikipedia.org/wiki/Solid_angle

Thanks!

Finally!

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