Re: Detecting the Oort cloud.

In message <1120918848.582339.148300@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Robert Clark <rgregoryclark@xxxxxxxxx> writes
Robert Clark wrote: 
Assuming Oort cloud comets have about the same reflectivity as known
comets, could the planned 100 meter telescopes resolve them at the 1
light-year distance of the Oort cloud?
 Current telescopes can not a disk for stars but detect them as point
light sources. Could a 100 meter telescope detect an Oort comet as a
point light source?
 Since there is theorized to be a cloud of comets there could a 100
meter telescope detect them as a cloud of objects if not individually?



Bob Clark 

Is the interferometry that can be done with radio telescopes dependent
on distance? That is, does being at longer distance make the accurate
combining of the different signals more difficult? I know there have
been successful experiments with one component of the array in orbit.
Could we place one component on the Moon?
Could we then detect Oort cloud comets at radio wavelengths?


Comets don't radiate at those frequencies - or indeed any others; they just reflect. Anyway, an interferometer isn't very sensitive; it just has much better resolution.
An Earth/Moon interferometer has certainly been proposed, though - look at <http://www.astro.virginia.edu/~rjp0i/museum/future.html>, for instance.
There was a proposal to use the Hubble Space Telescope to look for Oort clouds around novae. The idea was that the increase in radiation would evaporate the comets and the spectrum of the resulting water vapour and other gases would be detectable.
.

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