Space, Reflection: See Earth's Past in Mirror?

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SUMMARY

The discussion centers on the theoretical possibility of using a mirror in space to capture images of Earth’s past by reflecting light. It establishes that while light takes time to travel, introducing mirrors can create a slight delay, but this delay is negligible for practical purposes. The consensus is that setting up a mirror in space would not allow for significant historical imaging due to the time required for deployment. Ultimately, the idea of capturing images from the past using mirrors is impractical, as any setup would not yield results beyond the time of launch.

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  • Understanding of light travel time and its implications
  • Basic knowledge of optics and reflection
  • Familiarity with the concept of time delay in imaging
  • Awareness of practical limitations in space exploration
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Physicists, optical engineers, space exploration enthusiasts, and anyone interested in the theoretical implications of light and time in imaging technology.

atarah
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TL;DR
can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
 
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We don’t even need a mirror to produce that effect. When I see a fly land on a table 3 meters away…. The fly actually landed about 10 nanoseconds before I saw it land, because that’s how long it took the light to travel the 3 meters between the table and my eye. The same thing would happen if we were using a camera instead of a human eye to form the image.

And yes, sending the light on a circuitous path with one or more mirrors allows us to introduce yet more lag between event and eye. In practice however, we’re not going to be able to get more than a tiny fraction of a second of additional delay that way.
 
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atarah said:
Summary: can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
Unless the mirror is already there, getting it set up will require so much time that you'll not see any farther into the past than when you launched it.

So if you are planning on getting some long distance images of the grassy knoll at a particular historically relevant moment, you are out of luck.
 
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How about this view? It looked back 3 seconds in history.

1654605141806.png
 
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atarah said:
Summary: can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?

can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
Your bathroom mirror will give you a delay of ten nanoseconds or so. that would be a start!
 
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