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>> “Where’d you get that one from?” <<
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Logic!
Every comet is roughly co-planar with the Earth and the sun.
They can’t have come from the sun, so they had to come from the Earth. The notation of life sourced materials on this comet is the icing on the cake.
(or are you one of the kooks holding out for the imaginary “oort cloud?”)
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By that logic, every other planet is also roughly co-planar with the Earth and the Sun. Did all of them also come from
Earth, too?