Where does “Once in a Blue Moon” Come From? On August 30th, a rare Blue Moon is gracing our skies! This celestial phenomenon occurs when a full moon appears twice in a single month. 🌕 #BlueMoon #Astronomy #Space | Museum of Science, Boston

423K views · 25K reactions |   Tonight, there's a Blue Moon in the sky! A Blue Moon is a second full Moon in the same calendar month, and Halloween falls on a full Moon only once every nineteen years, on average. More NASA Moon facts: https://go.nasa.gov/3kMjpTp #NASAHalloween | NASA - National Aeronautics and Space Administration | Facebook