Q&A

# Post History

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posted over 1 year ago by Olin Lathrop‭

Planet 9 would certainly be "dim", but whether it would be dark according you your definition is impossible to say.
Whether a dimmer object fits your definition of "dark" can't be judged because the definition is too vague.  You define dark as not visible with a "normal" telescope.  The norm for telescopes, at least leading edge scientific ones, keeps progressing.  There is also huge variation in the light gathering power of scientific telescopes used today.  If you build a big enough mirror and keep other light away from it well enough (like putting it in space), then you can eventually see arbitrarily dim objects.  How big a mirror is "normal"?  3 meters, 10 meters, a much larger space telescope that might be normal before the end of the century?