A lovely cityscape view captured from a rooftop shows the Full Moon rising above the city of Lisbon. According to modern folklore, the second Full Moon in a calendar month is called “Blue Moon”. Rather than Blue, the rising moon can appear yellow-orange when it is near the horizon due to the way light scatters in the atmosphere. When the moon is low on the horizon, moonlight passes through more of Earth’s atmosphere than when it is overhead. By the time light reaches the observer, the blue and green light has already been scattered, leaving only the red-orange light. We’ve already had one Blue Moon in January 2018, and the last time this rare event of two Blue Moons occurred in such quick succession was January and March of 1999.