There's likely going to be a lot of people questioning this photo, and that's understandable. The person who took the photo is Eric Houck (@a_guy_named_eric), and I've followed his photography for a good amount of time. He's always been very transparent with how he does his photography (whether it's composites, how many, other editing, etc.), so I would be surprised if this was the exception. It's not unheard of that the sky have split colors at sunrise and sunset, see this photo.

His description.

Morning Glory. Believe it or not, this is a single shot!! Some extraordinary conditions produced these unique and amazing sunrise colors!

I have every reason to believe the photo is genuine, but it's obviously up to everyone to make up their own mind.