Telescope on the moon idea poopooed

[Vince1963]

When it comes to a radio telescope, considering the size it would have to be largely built on the Moon itself.

I maybe wrong on this one but radio telescopes don't need to be big do they?.....Just a lot of them in an "array",Is this right?.. also i don't think they need to be "dish shaped" (although as Keith says they could use a crater with the antenna suspended across its diameter), Can't they be like say a wire grid placed along the surface of the moon surface with upright antenna's?... Again i might be wrong (maybe someone can explain)

[TheMightyKong]

You have to be joking! You really mean that an amateur astronomer actually thinks that the moon has a dark side?

I don't believe it, I just don't B####y believe it!

so it's a rookie mistake. No need to ridicule the man.

[davew]

I rather think Peter Drew was joking ! If I could live to be 100 he will still have forgotten more than I would know

But you're correct, no need for ridicule.

[Vince1963]

I rather think Peter Drew was joking ! If I could live to be 100 he will still have forgotten more than I would know

But you're correct, no need for ridicule.

Are Vlad and Peter Drew the same person?

[Andymarrison]

If I'm remembering right here then the important thing is that the size of the reflecting dish (the equivalent of a mirror for visible light) is large enough in relation to the wavelength that is being observed (in this case radio waves, which encompass a very wide range of wavelengths, but let's say around a metre for the sake of this discussion) that diffraction effects don't dominate the image. So in other words the diameter of the dish needs to be many times the wavelength of the radio signal. Similarly, it's not necessary to have a nice smooth dish because the long wavelength radio waves don't "notice" imperfections in the surface as long as these are smaller than their wavelength - so some conducting wire mesh with holes of a few cm, in this case, wouldn't matter.