I have had a theory that maybe by placing an object like a large satalite rotating disc a certain distance away from the planet earth.

We can rotate the satalite at a reasonable speed to perform morse code or similar. Using the planet earth as a light and a disc type mirror to reflect the light.

Im sure this would be possible yet how much distance would it cover across space.

In theory star are extremely far away. Yet it one started flashing im sure we would notice it and visa versa.


closed as off-topic by Organic Marble, Nathan Tuggy, Mark Omo, DrSheldon, peterh Oct 15 '18 at 5:29

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  • $\begingroup$ I was thinking along the lines of being able to blackout the view of whole earth and make it visible again not so much a mirror. I think a mirror would just reflect. Yet being able to blackout the view of the planet on one side then make it re-appear could make a big impact if there are any other astronomers out there across the universe watching us :) $\endgroup$ – Daniel Lee Oct 15 '18 at 0:18
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    $\begingroup$ I'm voting to close this question as off-topic because it is unrelated to space exploration. $\endgroup$ – Organic Marble Oct 15 '18 at 2:06
  • $\begingroup$ It would be more effective if said mirror was reflecting the Sun's light rather than Earthshine (which it would anyway, for some orientations), but even then, it would be a very dim signal alongside the direct light of the Sun. $\endgroup$ – Anthony X Oct 15 '18 at 3:16
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    $\begingroup$ From very far away, Earth is very small compared to the Sun. The satellite would be so tiny that it is completely invisible from far away. $\endgroup$ – Uwe Oct 16 '18 at 15:43

It would be incredibly difficult to provide some kind of obvious signal to distant observers that isn't completely drowned out by the light of our sun. You'd have to obscure a significant portion of the sun's light in an obviously artificial way. This would involve creating something with an apparent surface area at least as large as earth's.

Another possible alternative is to detonate every single nuke we have, but I doubt that would create a gamma ray burst strong enough to be noticed.


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