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looking to the past



 
 
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  #1  
Old January 5th 04, 12:07 PM
Mr Jherek Chamaeleo
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Default looking to the past

is it theoretically possible to sense from earth the qualities of the light
that was reflected into space in the past from earth
could we focus on a certain distance in space say 1000 light years away to
build a visual image of the past


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  #2  
Old January 5th 04, 01:58 PM
Roger Hamlett
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"Mr Jherek Chamaeleo" wrote in message
...
is it theoretically possible to sense from earth the qualities of the

light
that was reflected into space in the past from earth
could we focus on a certain distance in space say 1000 light years away

to
build a visual image of the past

First, we can't even 'see' a planet at stellar distances (for a nearby star,
let alone one at 1000 light years away), both in terms of the amount of
light reflected from a local star, and in terms of the resolution needed.
Then add the fact that you can't 'see' reflected light, until it reflects
off something else. Add the albedo of the surface involved, and the fact
that the distances involved then double (and the amounts of light then
'quarter' - good old inverse square law), and the answer is 'no'. Not even
close...

Best Wishes


  #3  
Old January 5th 04, 02:32 PM
Greg Neill
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"Mr Jherek Chamaeleo" wrote in message
...
is it theoretically possible to sense from earth the qualities of the

light
that was reflected into space in the past from earth
could we focus on a certain distance in space say 1000 light years away

to
build a visual image of the past


You'd need to have something focus the light to form an image
on a surface of some sort. Perhaps a gravitational lens could
provide the focusing, but what of the projection screen?

Light is scattered from nebulae, so that won't do it. And to
add to the difficulties, the flux of light from our Earth at
the required distance would be so pitifully low as to be
entirely swamped by background light. You'd never be able
to make out an image.


  #4  
Old January 5th 04, 08:27 PM
Chuck Taylor
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"Mr Jherek Chamaeleo" wrote in message
...
is it theoretically possible to sense from earth the qualities of the

light
that was reflected into space in the past from earth
could we focus on a certain distance in space say 1000 light years away

to
build a visual image of the past


Only by imbibing more Rebel Yell than is legal.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
************************************************** **********



  #5  
Old January 6th 04, 05:13 AM
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"Mr Jherek Chamaeleo" wrote in message
...
is it theoretically possible to sense from earth the qualities of the

light
that was reflected into space in the past from earth
could we focus on a certain distance in space say 1000 light years away

to
build a visual image of the past


Yeah it is called red shift and CBR


 




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