Greg transplanted to Taos shortly after receiving his BFA from University of Texas in Austin, Texas. Greg creates works mainly in the mediums of oil and watercolor. Although originally know as a watercolorist, Greg has been concentrating on oil for the last five years. The switch in media has been a rebirth of sorts. Moon states "that a change has allowed me to take on subjects and technical problems that watercolor just can't fully actualize." Greg does still create through his first love, watercolor. "You never forget where you came from, and watercolor still informs me in a quick and direct manner that is impractical for me in oil."His watercolor style is more European, using more glazes and modeling with very little "wet into wet", like the California style watercolor which most Americans paint. Greg feels that because of the difference in these styles watercolor isn't given its proper respect in the United States. He believes watercolor is much more popular in Europe because they do more complete finished paintings. "Unfortunately most Americans still view watercolor as a sketch material", says Moon.

Greg has been doing nocturnal scenes for about ten years. He depicts night-time "because there is a lot of ambiguity in it and, yeah, mystery." Working with subjects outside the glare of sunlight gives him freedom he admits - he's not subject to the "tyranny of realism". He can create detail, then destroy it. The darkness that is so evident in his paintings is an attempt to convey emotions of his childhood and his love of the night-time. It draws him back to when he was a child, "playing Kick-the-Can or Hide and Seek and you hear your mother calling you when it's time to come in."

Greg has been showing professionally since 1989 in galleries and museum shows; at this point he has been participated in over 70 exhibitions.