Space and Astronomy in general

Nice!

That is so impressive. Can't wait to see what other pictures it sends back.

So cool! I should look up some papers ok the alignment technique.

SLS has taken its first trip (from the VAB out to the pad).

So those are all previously undiscovered galaxies I take it. Is that going to revolutionize our understanding of the universe or have prior estimates included galaxies we have yet to see?
I'm guessing its a little bit of both. We accounted for some measure of galaxies we had yet to see. But the Webb telescope is going to prove we low balled by a significant margin.
I mean, if every star we could barely see before has 50+ galaxies around it...

There should be fewer galaxies the further back in time we look, right...? Also, gravitational effects on a star's path could reveal unseen influences.

I don't think they're undiscovered. Hank only means we can't see that particular star with the naked eye. We knew where to look to test the JWST with it, which means it was already observed before, using more sensitive instruments.

I think we have yet to determine whether the JWST will be able to see more than our current crop of instruments could, or if it will simply see them better.

It's designed to see objects 9x fainter than Hubble can, meaning it can see further in distance and thus time. Since it's met and exceeded calibration goals, it follows that we *do* know that it will exceed current instruments.

So then, calling it the "observable universe" is a misnomer? Because if there's more universe that we can observe, it stands to reason that "universe that can be observed so far" is, while clumsier, more accurate. I figured that, like the Hubble deep field, it was just a matter of keeping Hubble watching long enough to collect enough light. And that JWST just made the time needed to do so much more reasonable.

JWST will see much further into the infrared than Hubble ever did, no matter how long their exposure times. That's important for ancient, distant galaxies, since they are moving away from us fast enough to be red-shifted into infrared.

https://jwst.nasa.gov/content/about/...

No, the term "observable universe" denotes what of the the full universe we can see today, based on the speed of light. It does not contain any notion that the universe we can see can't be expanded, that's a bit of a weird reading. But your sentiment is right.

The observable universe is a sphere that goes basically back to the co-moving distance of the particles that emitted the cosmic microwave background about 14B parsecs, and out about 14.3B parsecs to the co-moving edge of the observable universe. So both of those are radii of a sphere. Co-moving means that not only are we moving away from those original particles, the universe itself is also expanding.

Mind-blowing. All that said, what the JWST promises to do is to see more stuff further away *within* the observable universe. So it will increase the objects we know about, but not expand the edges of the universe from our perspective. I think I misremembered a bit earlier.

NSMike wrote:

So then, calling it the "observable universe" is a misnomer? Because if there's more universe that we can observe, it stands to reason that "universe that can be observed so far" is, while clumsier, more accurate. I figured that, like the Hubble deep field, it was just a matter of keeping Hubble watching long enough to collect enough light. And that JWST just made the time needed to do so much more reasonable.

The observable universe us based on the speed of light and the age of the universe. It's not dependent on the technology we use to observe it, so it doesn't change size every time the tools we use get upgraded. JWST doesn't increase the size of the observable universe, it just lets us do a better job of observing it.

I've always wondered that too. If we keep seeing things farther away, are we way off about the timing of big bang, size of universe, etc. What do we really know?

Stele wrote:

I've always wondered that too. If we keep seeing things farther away, are we way off about the timing of big bang, size of universe, etc. What do we really know?

Those things were already there in the bubble of the observable universe, we just didn't have the technology to see them before.

Stengah wrote:
Stele wrote:

I've always wondered that too. If we keep seeing things farther away, are we way off about the timing of big bang, size of universe, etc. What do we really know?

Those things were already there in the bubble of the observable universe, we just didn't have the technology to see them before.

Yeah, it helps if you recognize the silent "theoretically" in "theoretically observable universe".

Mildly off-topic:

I've been internally pronouncing "JWST" as "Juiced". As in "Yo, that space telescope is f*kin' JUICED!"

Anyone with me?

Stele wrote:

I've always wondered that too. If we keep seeing things farther away, are we way off about the timing of big bang, size of universe, etc. What do we really know?

The age of the universe is derived primarily from the wavelength and strength of the cosmic background radiation, which we can see quite easily and was confirmed by a telescope called COBE. It's unlikely that will change drastically, but we might reduce the error bars on the estimate.

NSMike wrote:

I don't think they're undiscovered. Hank only means we can't see that particular star with the naked eye. We knew where to look to test the JWST with it, which means it was already observed before, using more sensitive instruments.

Correct. Most of the galaxies in those images have been seen before using ground-based telescopes or the Spitzer Space Telescope. This is a pretty short exposure with JWST, so more is definitely to come.

A comparison of this JWST image with an image taken previously by the Spitzer Space Telescope...this shows the kind of improvement we're getting with a factor of 10 increase in resolution and 100+ times larger mirror collecting area!

IMAGE(https://raw.githubusercontent.com/gbrammer/jwst_EERS/main/jwst_irac_compare.gif)

With regards to the star itself: it's no big deal that the you can't see it with the naked eye. In the visual, it's >100x too faint to see with your naked eye, but our eyes are very small telescopes. You could see this star with binoculars. In fact, if any of you use Stellaris (free!) or other planetarium apps, you can look it up. It's in the constellation Draco. The name of the stars is TYC 4212-1079-1. Well, one of its names...

That picture shows what I was talking about, no?
The blurriness of the first picture obscures all but the largest dots/galaxies.
Plus there are even some blurry small dots in the Juiced image...

As for the "visible universe" part of the discussion: the furthest we could physically see is about 45 billion light years from the Earth. While light has only traveled for about 13.7 billion years (assuming our standard cosmology is correct), the Universe expanded quickly enough that the most distant galaxies from which we could collect light are currently 45 billion l.y. away or so. There certainly could be more of the Universe than captured in our "horizon," as it's called.

Having said that, we can't see galaxies that far away. They are very often too faint and their light is shifted into the infrared, where our instruments have been less advanced. JWST will help that. Though it will get nowhere close to detecting the first stars, as those will be way too faint even for this telescope.

Incidentally, there seems pretty good evidence that Webb himself was a bigot responsible for charting NASA toward a harsh "no gays" policy. There was a movement to get NASA to change the name. It went nowhere, and NASA never shared any of their findings on the matter. Recent documents have revealed that it was likely a pretty biased approach, with lots of people giving NASA Administrator Bill Nelson cover for not changing the name.

fangblackbone wrote:

That picture shows what I was talking about, no?
The blurriness of the first picture obscures all but the largest dots/galaxies.

The blurriness is part of it: galaxies are washed out into the background (or into one another), making them hard to pull out. Mostly not due to blurring with that particular star (though that raises the background a bit), but just generally blurred into undetectability.

But the larger number of galaxies is also the sensitivity to light due to the larger collecting area, more efficient optics, and better detectors. Even for a short exposure, there are lots of galaxies in the JWST image not detected at all by Spitzer.

firesloth wrote:

As for the "visible universe" part of the discussion: the furthest we could physically see is about 45 billion light years from the Earth. While light has only traveled for about 13.7 billion years (assuming our standard cosmology is correct), the Universe expanded quickly enough that the most distant galaxies from which we could collect light are currently 45 billion l.y. away or so. There certainly could be more of the Universe than captured in our "horizon," as it's called.

That's kind of what I'm getting at and the part I don't really understand about big bang.

If universe is x old and nothing travels faster than the speed of light then how can anything be farther than x light years away?

Because space is *also* expanding?

Robear wrote:

Because space is *also* expanding?

Yes, that's exactly why.

And worth noting that for 2 points in space sufficiently far apart, they are moving away from each other at a speed faster than light, meaning people at point A will never see people at point B no matter how powerful their telescopes are.

Chairman_Mao wrote:

And worth noting that for 2 points in space sufficiently far apart, they are moving away from each other at a speed faster than light, meaning people at point A will never see people at point B no matter how powerful their telescopes are.

Stele wrote:
Chairman_Mao wrote:

And worth noting that for 2 points in space sufficiently far apart, they are moving away from each other at a speed faster than light, meaning people at point A will never see people at point B no matter how powerful their telescopes are.

:shock:

The Douglas Adams quote comes to mind here:
“There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.“

Stele wrote:
Chairman_Mao wrote:

And worth noting that for 2 points in space sufficiently far apart, they are moving away from each other at a speed faster than light, meaning people at point A will never see people at point B no matter how powerful their telescopes are.

:shock:

Try squinting.