no pink is not in the rainbow or even in the color spectrum it is in fact a color made up in the mind here read this (show Radiolab noted that there is no pink in the colors of the rainbow. Pink is actually a combination of red and violet, two colors, which, if you look at a rainbow, are on the opposite sides of the arc)
It is possible. Pink is a mixture of colors. Especially red and white with a tinge of blue. Everything is available in the sky? Blue, red from the rainbow and white from the sun. It depends on how you look at the rainbow.