You could wait 27 days or you could see it everyday. What is it?
The moon. Even though the true moon cycle is about 29.5 days, it takes 27 days, 7 hours, and 43 minutes for our Moon to complete one full orbit around Earth. Thus you can see the full moon every 27 days or you can moon yourself every day in the mirror. Not that you’d want to. Does anyone moon themselves? Can’t say as I’ve ever had the “pleasure”.