Exciting name aside, you shouldn't expect the Blue Moon to undergo any dramatic transformations in color this weekend — other than the mesmerizing orange-red hues seen around moonrise and moonset, as its light passes through the densest part of
Earth's atmosphere.
Instead, we use the term "Blue Moon" to describe the second
full moon that rises in a single calendar month. This rare event occurs roughly once every 2.5 years, as a result of the difference in time between a month of the Gregorian calendar and the 29.5 days it takes
the moon to cycle through its first quarter, full, third quarter and new moon phases.