This moth is named after the Roman goddess of the moon, Luna. It is part of the Saturniidae family that includes the Giant Silkworm moths - although these aren't the same as the silkworm moths that are used for commercial silk production.
This moth was on the frame of my front door last summer. I'm going to guess the wingspan was almost six inches. He was bigger than the palm of my hand. This is a male - the antennae of the male moths are more feathery than the female. And yes, the colors in the picture here are true to life - he was really this lime green with the pink and purple accents.
Until about three years ago I had never seen one of these and since we moved into out house by the woods, we see a few each summer. Sometimes they appear as early as March and as late as the end of July. Apparently in my climate they can go through 2-3 life cycles in that time period. The moths are short lived and don't actually eat. The adult life span is only a week or so; just long enough for mating. The caterpillars actually eat before spinning their cocoon and that is enough to get the moth through its short life. The caterpillars like to eat Sweetgum, Persimmon, and Walnut tree leaves. The moth often lay their eggs on the underside of the leaves.
I know the woods around our house are full of Sweetgum trees; so maybe that is why we see so many in our yard. We usually only see the moths at night but sometimes we are lucky enough to see them when there is still daylight left and get a picture. I have only seen one moth so far this year. Hopefully there will be some more this year because they truly are an amazing site to see.