Somewhere over the rainbow, during Bein Hashmashot, the time “between the suns” — twilight — the rainbow was created. At least according to the Mishnah in Avot 5:6.
The rainbow does not appear on our radar until this week’s parsha, where it serves as a sign of the covenant between G-d and mankind that the world should never be destroyed by flood again (Genesis, chapter 9).
And G‑d said to Noah and his sons: I will keep my covenant with you and your descendants… and never again will a flood destroy all life, and there will not be another flood destroying the earth…. This is the sign I am making, testifying to the covenant between Me and you and all living souls, forever.
I have put my rainbow in the clouds, and it will be the sign of the covenant between Myself and the world. When I send clouds over the earth, the rainbow will be seen in the clouds, and I will remember the covenant between Myself and yourselves and all living souls, and there will never again be a flood to destroy all life. The rainbow will be in the clouds and I will see it and remember the eternal covenant between G‑d and all the living souls on earth.
If you ask any little girl about the most drawn phenomena of nature — after unicorns, that is — the answer would be rainbows. While writing, I asked my fourth grader when she had last drawn a rainbow. Only a couple of hours before our conversation.