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Old 11-13-2019, 07:11 PM
 
Location: Raleigh, NC
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Seems like there's lots of money into extremely large telescopes planned (ELT). What exactly would we be able to see with these extremely large telescopes that are ground based vs the James Webb telescope in L1 or L2 orbit?

They say the European ELT will be able to spot extrasolar planets, direct imagine and identifying the atmosphere of these planets. That sounds like James Webb to me. What are the advantages of the very expensive James Webb as compared to this one then? This one is being built in Chile.

I would want a telescope to show me actual pictures of other planets. Would this European ELT and the James Webb do this? Of course, they should be able to determine the atmospheric composition of these planets as well.

The other large telescope in Hawaii, is being met with protests due to sacred land, the Thirty Meter Telescope (TMT).


Check out this comparison picture of the size of these things!




https://www.eso.org/public/usa/teles-instr/elt/




Here's that large European ELT under construction, hopefully done by 2025 in Chile:


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Old Yesterday, 12:19 PM
 
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There are certain advantages to each. The James Web Telescope is designed primarily to operate in the infrared wavelength which will enable it to look further back into time to see the earliest stars and galaxies, and also to penetrate the dust clouds which visible light is unable to in order to see the formation of stars and planets that are inside of those dust clouds. For that purpose the JWST will be superior to ground based telescopes. Since water vapor in earth's atmosphere absorbs most infrared radiation the James Web telescope will be superior to any high altitude ground based or air-borne infrared telescopes.

However, ground based telescopes can be built larger and less expensively than space telescopes like the James Web telescope. They are easier to maintain and repair. It anything goes wrong with the JWST we currently won't be able to reach it to make repairs.
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Old Yesterday, 01:19 PM
 
Location: Seattle
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The magnitude difference between a star and its planetary companion is lower in the infrared, making the planet easier to image when it is close to the star.
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Old Today, 04:48 PM
 
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Quote:
Originally Posted by Mike555 View Post
There are certain advantages to each. The James Web Telescope is designed primarily to operate in the infrared wavelength which will enable it to look further back into time to see the earliest stars and galaxies, and also to penetrate the dust clouds which visible light is unable to in order to see the formation of stars and planets that are inside of those dust clouds. For that purpose the JWST will be superior to ground based telescopes. Since water vapor in earth's atmosphere absorbs most infrared radiation the James Web telescope will be superior to any high altitude ground based or air-borne infrared telescopes.

However, ground based telescopes can be built larger and less expensively than space telescopes like the James Web telescope. They are easier to maintain and repair. It anything goes wrong with the JWST we currently won't be able to reach it to make repairs.
That's a good summation of the pluses and minuses for both types of telescopes.

On a side note, if anymore is passing through Tucson, Arizona, and you like to see really cool, science stuff, I highly recommend a tour of the Richard F. Caris Mirror Lab at the University of Arizona, it's under the east side of the football stadium.

Tours - Richard F. Caris Mirror Lab - University of Arizona

They are currently working on the mirrors for the GMT (Giant Mellon Telescope) being built in Chile and they also made the twin mirrors for the Large Binocular Telescope up on Mt. Graham in Southern Arizona.
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Old Today, 06:55 PM
 
Location: Omaha, Nebraska
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^^^That sounds like a really cool place to visit! Guess I need to plan a trip to Tucson!
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Old Today, 07:50 PM
 
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Originally Posted by Aredhel View Post
^^^That sounds like a really cool place to visit! Guess I need to plan a trip to Tucson!
Well worth it, especially if they are starting to cast a new mirror or polishing a just completed mirror or doing both!

It looks like they still have to cast three more 8.4 meter (27.5 feet) mirrors for the Giant Magellan Telescope in Chile. They already cast five of them, including the center one and the reason they are making 8, instead of just 7, is because they need to use the extra one to swap it in and out to do preventive maintenance on the other mirrors once the telescope is up and running.

It will be quite interesting to see how they get all of the mirrors from Tucson down to the Las Campanas Observatory in Chile. I know for the Large Binocular Telescope, they had a specially designed cradle that the mirror sat in at an angle so it didn't move at all and they placed a protective covering over the mirror's surface so it's not damaged while in transit.

I assume they will probably truck the mirrors, one at a time to Port Hueneme or Long Beach outside LA and ship them by boat down to Valparaíso (major port) in Chile, then truck them from there up to Las Campanas. The logistics are crazy for projects like these!
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