Author Topic: How big can we make a Telescope?  (Read 630 times)

falkwinsliche

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Re: How big can we make a Telescope?
« Reply #15 on: January 25, 2018, 08:20:14 PM »
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inmactoopho

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Re: How big can we make a Telescope?
« Reply #16 on: January 26, 2018, 01:40:23 AM »
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But of course, you would have to have everything aligned perfectly.
I design It so its self aligning.

Daniel Ross

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Re: How big can we make a Telescope?
« Reply #17 on: January 30, 2018, 11:22:12 PM »
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But of course, you would have to have everything aligned perfectly.
I design It so its self aligning.[/quote]
With a 17500 mph orbiting satellite? Good luck with that!

Jaye Agting

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Re: How big can we make a Telescope?
« Reply #18 on: January 30, 2018, 11:55:57 PM »
The Aricebo Radio Telescope dish is 305 meters across; that's over 1000 feet.

Jerome Fountain

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Re: How big can we make a Telescope?
« Reply #19 on: January 31, 2018, 01:32:57 AM »
Sadly it doesn't look like it's in good shape as of 2015 and I bet its even worse after the hurricane season this year. Or does all that dirt do anything to the reflectivity of the dish?

risodachest

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Re: How big can we make a Telescope?
« Reply #20 on: February 03, 2018, 07:11:57 AM »
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Throwing the weight issue out of the way, how big could we make a telescope before the light from the center would be too quick for the light from the edges to travel to the focuser and make an image distorted? Or could this even be an issue and I am just making a fool out of myself?

How about the size of the moon. We actually used it to observe the sun with I think the Hubble, for the Venus transit.

So the moon is the reflector and the Hubble the eyepiece.

I have a design, carved into the side of a mountain thats a mile in dia.
Very interestingconcept! But of course, you would have to have everything aligned perfectly. And if you messed your focal length up by a few nanometers you could have your focal point 100 miles too far or too close. But in theory, it would work.
No, if you messed up your focal length by a few nanometers, your focal point would be only a few nanometers out.

AIUI, the use of the moon during the Venus transit was not for imaging - rather it was to allow a spectrographic analysis of the diffuse reflected light so that any changes due to atmospheric absorption in Venus's atmosphere could be measured.

https://sservi.nasa....-venus-transit/

James Runninger

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Re: How big can we make a Telescope?
« Reply #21 on: February 09, 2018, 12:11:00 AM »
Regarding imaging, there is no upper limit to the size a true, perfect paraboloidal mirror. It will phase all light perfectly together at its on-axis focal point, whether its aperture is 2 meters or 2 light-years. Interesting issues come up for a 2 light-year diameter mirror, however. You'd have to refocus on nearer stars relative to, say, quasars. That would add in a little spherical aberration. You'd also have to be careful at or near focus, as the full energy radiated from the star toward the 2 light-year paraboloid would be present (neglecting reflection losses, of course)

Devon Dank

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Re: How big can we make a Telescope?
« Reply #22 on: February 09, 2018, 10:48:51 AM »
Well beyond a certain size it could only be made with a sub diameter lap....something like an Ohio class.