How did Jor-EL Know Of earth

[Doug Barr]

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  Have you ever wondered, before you had been provided with an "answer" (which by now there have probably been many) just how it was that Jor-EL Knew of Earth, so many light-years away. Not only did he know of its existance, but also that Kryptonians would be nourished by its atmosphere, & would have Super powers here?
 I realize they are a very advanced race, but wouldnt any race so advanced have more than one scientist who knew their planet Krypton was about to end? Jor-EL was scourned for even implying it! Why?
  I like to think, just in my own imagination, that Krypton had a close relationship with Oa, the planet which is home to' The Guardians of the universe'. Anyone familiar with 'Green Lantern' ( & it is well worth becoming familiar with) knows that the Guardians have the Galaxy pretty much mapped out, It would not be a stretch to believe they would be aware just what effect Earth would have on a Kryptonian.
   But why did the Kryptonians doubt Jor-EL? Could it be that the Guardians were nervous about having ALL the kryptonians migrate to a planet where they would be virtuall Gods?What would become of the Earthlings? Was it the Guardians who told the Kryptonians that Jor-EL was wrong?
 I have another reason why they let, or rather told, Jor EL he could send a baby there, to be raised as a earthling.
It gets a little complicated, I will edit this post later on as I work it out clearer,It has to do with Krypton being part of the same sector as Oa(in my telling, anyway), & that the whole sector was dying, as Krypton did. Life didnt evolve on Kyypton, it migrated there as other planets in the sector were dying. Life COULDNT develope on Krypton - the gravity was too dense.
   If the sector was dying, how did Oa survive? It didnt, on a physical plane. but I am still working on this,.

[Composite Superman]

As I recall, Jor-el had a really powerful telescope, although I may be thinking of Zor-el (who knew of Kal-el being on Earth before he sent Kara there). As for why the Kryptonians didn't believe Jor-el, the explanation has probably changed with different tellings of the tale, but it's mostly because the story requires it.

[NotSuper]

I know that Zor-El used the super-telescope, and I think that Jor-El had one as well.

[MatterEaterLad]

Even as far back as the the mid 1930s original strip, telescopic observation was mentioned...

https://www.supermanthroughtheages.com/tales2/adventurestrip/?page=8

That's my favorite telling, I'm not so much a fan of the Oans being involved in everything, but that's just me...

[Doug Barr]

Yes, the telescope theory. Lets say you had a telescope powerfull to view a planet God only knows how many light-years away, how would it be able to determine that Kal-EL would be invulnerable there?   But The Guardians would have known. They would also have been wise enough to only allow a newborn to go, who would be raised as an Earthling. Because the temptation of The  Kryptonians to rule the world with those powers might have been too great, the course of history would have not merely altered, it would have been re-written in Kryptonese.The guardians could not allow that, so they informed the Kryptonian council that Jor-EL was in error about his theory that Krypton was about to die.
 But anyway, my originall post was put badly, what I meant was, if there were no explination for how Jor-EL knew all about earth, & YOU had to create one, how would you say he knew?
 Think of the possibilities. It could have involved Gen.Zod, Zod could have discovered that on this far-away planet kryptonians could be God-like, This could have then been the reason Jor-EL imprisons Zod. Or something else. I would like to hear your ideas if you come up with any.