Re: Detecting the Oort cloud.
- From: "Tom Van Flandern" <tomvf@xxxxxxxxxxxxx>
- Date: Sun, 10 Jul 2005 00:37:05 -0400
This responds to Jonathan Silverlight and Robert Clark.
"Jonathan Silverlight" <jsilverlight@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
writes:
> Given that the Oort cloud is supposed to contain a trillion (million
> million) objects, shouldn't we be seeing occultations of stars? There
> should be several thousand in front of a globular cluster like M13,
> for instance.
No, the angular diameter of comets at that distance is too
small to occult a star. One kilometer at 43,000 au subtends an angle of
just 0.03 micro-arcsec. And even a trillion comets mean just two per
square arcsec on average. At best, a comet might have a rare transit in
front of a star, but not block enough light for the brightness dip to be
detected.
and "Robert Clark" <rgregoryclark@xxxxxxxxx> writes:
> Could we then detect Oort cloud comets at radio wavelengths?
Comets are not radio sources. They would therefore be
invisible at radio wavelengths. -|Tom|-
Tom Van Flandern - Washington, DC - see our web site on replacement
astronomy research at http://metaresearch.org
.
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