See Earth's Surface from the Past: Resolution Possible?

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Discussion Overview

The discussion revolves around the feasibility of observing Earth's surface from the past by catching up to or observing light reflected from Earth. Participants explore the theoretical implications of resolution and visibility of objects such as people or animals from astronomical distances.

Discussion Character

  • Exploratory, Debate/contested, Conceptual clarification

Main Points Raised

  • Some participants propose that if one could "catch up" to the light reflected from Earth, it raises questions about the resolution achievable and whether it would allow visibility of people or animals.
  • Others argue for a practical approach, suggesting that observing Earth's reflection from a distant object might be more feasible, though the challenge lies in identifying sufficiently reflective bodies and their locations.
  • A participant clarifies that one cannot catch up to light since it travels at the fastest speed in the universe, and the resolution depends on the observing instrument used by an alien in another star system.
  • Another viewpoint states that the resolution remains constant regardless of the method of observation, emphasizing that viewing Earth from Alpha Centauri would show it as it was 4.4 years ago, irrespective of the travel method.
  • One participant expresses skepticism about the visibility of small objects like people or animals from astronomical distances, arguing that the light reflected from Earth becomes too dispersed to collect enough photons for such observations.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of observing Earth's surface and the implications of resolution, indicating that multiple competing perspectives remain without consensus.

Contextual Notes

Limitations include assumptions about the capabilities of telescopes, the nature of light dispersion over astronomical distances, and the definitions of resolution in this context.

GreenAce92
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If you can "catch up" to the light reflected from the Earth at that time in the past. What kind of resolution would you get? Could you zoom into the surface such that people/animals could be visible.
 
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A more practical approach would be to observe the reflection of Earth from some distant object, given that nothing can overtake a photon. What kind of distant body would be sufficiently reflective, and where to look for one, is an issue.
 
Sadly, you can't "catch up" to the light that was emitted by the Earth since light is the fastest thing in the universe.

But if you're asking what an alien in another star system might see, then it really depends on what he is using to look at the Earth. The bigger the telescope, the better resolution he will have.
 
The resolution is the same.

Imagine looking at the Earth from Alpha Centauri right now, you'll see the Earth as it was 4.4 years ago.

The view will be the same weather you traveled via a hot air balloon or via instantaneous teleportation.
 
I would say that at astronomical distances, the light reflected by the Earth (which is not that much to start with) gets so spread into space that looking from any single definite location it would be practically impossible to see anything of the size of a person or an animal, no matter how big your telescope was. The amount of photons you could collect would simply be too small.
 

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