Amazing James Webb Space Telescope

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RobertOToole
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Amazing James Webb Space Telescope

Post by RobertOToole »

Ran across this the other night and I expected the technology to be impressive but I didn't think it would be blown away.
The optics are really beyond what I expected and the info on filters was very interesting.

If you have some extra time, check it out!

James Webb Space Telescope


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Link for info on Optics:


https://jwst-docs.stsci.edu/jwst-mid-in ... ocal-plane



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Link for info on filters:


https://jwst-docs.stsci.edu/jwst-mid-in ... dispersers

Scarodactyl
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Re: Amazing James Webb Space Telescope

Post by Scarodactyl »

I will admit the working distance is astonishing.

Pau
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Re: Amazing James Webb Space Telescope

Post by Pau »

Scarodactyl wrote:
Wed Jan 19, 2022 1:44 pm
I will admit the working distance is astonishing.
But despite delivering excellent angular resolution, magnification can't be high :lol:
Pau

Lou Jost
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Re: Amazing James Webb Space Telescope

Post by Lou Jost »

Nice to see they have a pair of filters in the visible spectrum! We'll probably soon be able to get that data ourselves for use in our own astroimagery, as with Hubble imagery (all Hubble data is freely available after a short embargo).

ModelZ
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Re: Amazing James Webb Space Telescope

Post by ModelZ »

For all of us struggling to get our simple, mundane equipment aligned and running... NASA guys need only half a year to get all those mirrors & detectors to line up! Anyone who has witnessed a rocket launch knows that the shaking (even at the distance of of mile) is pretty serious.

MarkSturtevant
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Re: Amazing James Webb Space Telescope

Post by MarkSturtevant »

I have been watching its slow deployment and progress on a couple web sites, and am getting slightly less nervous about it as it seems to be going so smoothly. But I have not seen these internal diagrams! That is gob-smackingly awesome.
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Chris S.
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Re: Amazing James Webb Space Telescope

Post by Chris S. »

The Webb telescope is a wonder. I can't to see what we learn from it.

My microscope-objective-oriented brain keeps balking at the idea of an imaging range that tops out at visible-spectrum orange and goes way down into infrared. "Resolution will be terrible!" says my intuition. But then I remember that this long-wavelength light is less perturbed by dust in space, and will let us examine red-shifted portions of the universe. And I really have no idea how resolution relates to wavelength in telescopes.

If no one minds, I'll move this thread to "General Discussion Forum and Community Announcements," once everyone has had a chance to read this.

--Chris S.

Lou Jost
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Re: Amazing James Webb Space Telescope

Post by Lou Jost »

Chris, yes, the far infrared light goes right through dust clouds, so it can image the stars that are completely blocked by dark nebulae. Also, there are a few stars that emit only in the infrared.

The Spitzer telescope already does this, though not as well as the James Webb telecsope will. You can check out these infrared results by searching on Spitzer infrared stars nebulae. You can also actually freely download all Spitzer (https://irsa.ipac.caltech.edu/Missions/spitzer.html) and Hubble (https://hla.stsci.edu/) raw data and play around with it yourself!!!

Here is a low-res comparison of the Milky Way in different wavelengths:
https://asd.gsfc.nasa.gov/archive/mwmw/mmw_sci.html

MarkSturtevant
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Re: Amazing James Webb Space Telescope

Post by MarkSturtevant »

I am not sure, but I believe its optical capabilities will include more conventional wavelengths too. Don't quote me on that, though.

There are different reasons for specializing in the infra-red. Besides being able to penetrate thru nebula, I think the telescope will be able to analyze the atmospheres of extra-solar planets. Think about what this could mean for the search for extraterrestrial life.
But a definite reason for seeing in the infra-red is so that it can see light from the early universe. Light from objects at greater distances is older light. The sun you see is from about 9 minutes ago. The Andromeda galaxy that you see (you can see it with the naked eye), is as it was about 3 million years ago. So when you look at that, you are seeing light from a time when only Homo erectus lived in Africa. Our species did not exist yet.
By being able to look at great distances, the JWST will see the universe as it was as the first galaxies and stars were forming. The thing is, though, because the expanding universe is accelerating in its expansion, because of a weird thing called dark energy, light for those distant times is stretched well into the infra-red range. So the JWST needs to be excellent at seeing in those wavelengths to see any of that at all.
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Lou Jost
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Re: Amazing James Webb Space Telescope

Post by Lou Jost »

The thing is, though, because the expanding universe is accelerating in its expansion, because of a weird thing called dark energy, light for those distant times is stretched well into the infra-red range.
Yes, but just to clarify, the red shift is very large even in a steadily expanding univese. The acceleration of the universe at present contributes almost nothing to the red shift. It needs a few tens of billions of years before it will matter.

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Re: Amazing James Webb Space Telescope

Post by Pau »

I've also read that the JWST can see orange and red light although I find estrange the notation of the filters: the scale of the graphs is in micrometres, not nanometres, and the filters in them and at the pictured wheels begins by "F560W": 560nm?, 5.6µm? ...?
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Lou Jost
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Re: Amazing James Webb Space Telescope

Post by Lou Jost »

The graph shows that the telescope sees down to 500nm, cyan-green. But it can only distinguish two colors in the visible range.

Pau
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Re: Amazing James Webb Space Telescope

Post by Pau »

...but it says Wavelength µm. 5µm are 5000nm, well into the IR, not 500nm, maybe a typo .

In a textbook I wrote years ago the illustrator didn't like the aesthetics of thousands and changed them for hundreds ruining the sense of the graph :evil:
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MarkSturtevant
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Re: Amazing James Webb Space Telescope

Post by MarkSturtevant »

Lou Jost wrote:
Mon Jan 24, 2022 12:07 pm
the red shift is very large even in a steadily expanding univese. The acceleration of the universe at present contributes almost nothing to the red shift. It needs a few tens of billions of years before it will matter.
Because of acceleration, the very very far objects (read as objects from early universe) are so red-shifted that their light is in the infra-red to us. At least that is what was explained on a YouTube video about the telescope and why it needs to see in those wavelengths to look back so far. Its pretty boggling to have to think that those things are both very far and from very long ago.
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rjlittlefield
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Re: Amazing James Webb Space Telescope

Post by rjlittlefield »

MarkSturtevant wrote:
Mon Jan 24, 2022 12:55 pm
Because of acceleration, the very very far objects (read as objects from early universe) are so red-shifted that their light is in the infra-red to us. At least that is what was explained on a YouTube video about the telescope and why it needs to see in those wavelengths to look back so far. Its pretty boggling to have to think that those things are both very far and from very long ago.
All that is correct, except the part about "Because of acceleration". That should read "Because of expansion of the universe".

Even if the expansion were decelerating, as was thought for a long time, the redshift would still be present and in a similar amount. The acceleration due to dark energy is indeed very weird, but as presently understood it's not the primary reason for the redshift.

--Rik

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