You really piqued my curiosity with that bit! As an Archaeological Steward for the State of Texas, I define "artifact" as
"an object with evidence of being formed, modified or used by an intelligent being".
AFAIK, "Intelligent being", is basically limited to the genus, Homo.
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If you have actual data re artifacts from planets / satellites other than Earth, please share them...
I am absolutely sure that Angels are intelligent beings. As beings I would apply the axioms as often offered by Alamo_Girl on these threads: 'without space things do not exist; without time events do not occur.'
I see God's copyright notice all over the cosmos in the unreasonable effectiveness of mathematics in natural sciences (Wigner). I'm seeing it again in the recent observation of gravitational waves.
And back in the 1960's when observations first showed there was a real beginning of space and time (the universe is expanding) - that too was a artifact of The Intelligent Creator ex nihilo.
I also see the artifact in the anisotropy of the early universe (thank you, TXnMA) - and in information (successful communication) in molecular biology, and the very existence of space/time, inertia, consciousness/mind and soul/spirit.
But, alas, people who do not look - or cannot see - or refuse to see - or see but resent God the Creator - will ever be looking for ways to posit a naturalistic explanation no matter how absurd it might be (emphasis mine:)
We take the side of science in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism.
It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to create an apparatus of investigation and a set of concepts that produce material explanations, no matter how counter-intuitive, no matter how mystifying to the uninitiated.
Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door. " - Lewontin in reviewing Sagan's book