Re: Under the Mirror Moon

On Aug 14, 9:16 pm, JennyB <jennybr...@xxxxxxxxxxxxxx> wrote:
This is something I discussed a few months ago on soc.history.what-if,
and it seems relevant to the SETI thread:

Suppose the event that formed the Moon was somewhat different, and
resulted in two Earth-like planets revolving round each other, and
eventually settling into geosynchronous orbit?

<quote from DougL>
Geosynch for us is 6.6 Earth Radii from the center of the Earth. The
fact that the mass of *Luna is NOT negligable will change this, I get
a distance of 8.33 Radii to retain our current day length based on a
back of the envelope calculation.

The full *Luna fills about 13.5 degrees in the sky as opposed to the
full moon (or the sun) filling about 0.5. *Luna will be over 2000
times as bright as the moon (about as bright as a well lit room).

And note that near midnight EVERY night it will be full as *Luna goes
from half waxing to half waning each night. And parts of *Luna will be
eclipsed EVERY night and there will be a full eclipse somewhere on the
*Earth EVERY day near noon. *Luna will NEVER be visible over half the
*Earth since both bodies are tidally locked.

All of this is also true if you switch *Luna and *Earth, the two are
in symetric situations.

The eclipses will routinely be total, but will NOT result in complete
darkness since the other body's atmosphere will refract light onto the
shadowed portions of the other body.

Anything which evolves on the near side will likely evolve for more or
less continuous light. I'll assume that any *Humans evolved on the
"dark" side of the *Earth and then migrated onto the more interesting
side to avoid questions of altered evolution. (Hey, *Africa really is
the dark continent!)
</quote>

By "continuous light", I take it that Earth-light is meant, not
sunlight. Earth-light is not very much, as we've established by
dgoing to the moon. I perceive you've gotten around that by having
the twin worlds much closer together. There's still gonna be a
difference between night and day. Then again, even starlight would be
enough to see by if your eyes were good enough. But we're also not
allowing for weather.

If *Humans have evolved on *Earth, is there also necessarily life on
*Luna, which shares its basic geology. I would guess so, but have no
idea how different it might be, since the two planets have different
detailed histories (for instance, they are hil at different times by
different big rocks).

Now imagine you are a *Human scientist with an Enlightenment level of
technology, looking at *Luna for the very first time. Your conjecture
is that there is intelligent life Up There.

How would you test it?


All I've got is a telescope, I guess, unless you give me a
spectroscope. I can look for vegetation, maybe town lights. Smog.

If they cut down all their forests, then we conclude "no intelligent
life".

.

Relevant Pages

  • Under the Mirror Moon
    ... Geosynch for us is 6.6 Earth Radii from the center of the Earth. ... The full *Luna fills about 13.5 degrees in the sky as opposed to the ... times as bright as the moon. ... Anything which evolves on the near side will likely evolve for more or ...
    (talk.origins)
  • Re: The Astronomers Giveth and the Astronomers Taketh Away
    ... Both Earth and Luna can be considered as ... Iow if Luna were about one-third more massive (or was ... For the Moon, that would be the Sun, by a factor of 1000. ...
    (rec.arts.sf.written)
  • Re: Under the Mirror Moon
    ... Geosynch for us is 6.6 Earth Radii from the center of the Earth. ... The full *Luna fills about 13.5 degrees in the sky as opposed to the ... Anything which evolves on the near side will likely evolve for more or ... If *Humans have evolved on *Earth, is there also necessarily life on ...
    (talk.origins)
  • Re: Under the Mirror Moon
    ... Geosynch for us is 6.6 Earth Radii from the center of the Earth. ... The full *Luna fills about 13.5 degrees in the sky as opposed to the ... Anything which evolves on the near side will likely evolve for more or ... idea how different it might be, since the two planets have different ...
    (talk.origins)
  • Re: AKICIF: Full moon on Friday the 13th
    ... > the earth will be uninhabitable in only a few hundred million years. ... A glancing collision between Luna and Venus would also cause enormous ... Since the density of the Moon and Mars are roughly the same, ... I wonder how much alpha could vary without killing us. ...
    (rec.arts.sf.fandom)
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