Or a gigantic obstruction: https://www.nasa.gov/content/the-aragoscope-ultra-high-resol...

Sadly the occulder has to be smooth at sub wavelength scales, or solar system bodies could be used.

I couldn't find a quick summary to this question. But what size aragascope do you need to achieve the equivalent of an x meter aperture?

My gut says probably the same size, but the claims suggest the aragascope can actually be smaller. My gut can also imagine it depends on the distance between the aragascope and the telescope.

> the claims suggest the aragascope can actually be smaller.

This may be because of the shape of the PSF is different from the normal airy disk one.

Here is a random google result showing the spot of arago, https://www.lighttrans.com/use-cases/application/observation... -- which looks to me like it would have poor contrast but good resolution. Though I'm out of my depth so it could be nonsense. :P

Edit: Ah, yeah the graph at figure 9 in the report linked on the linked page shows something like that.

The synopsis on the site suggests the same size as the disk. But I guess it doesn't say it scales the same as with mirror size.

> can be used to achieve the diffraction limit based on the size of the low cost disk, rather than the high cost telescope mirror