A full moon, known as the harvest moon, ushered in October on Thursday night. The name harvest moon is assigned to the full moon that occurs closest to the autumnal equinox each year, the standard time when farmers are in the fields harvesting their crops.
But in rare occurrence fitting 2020, this October will also end with a second full moon – on Halloween no less – known colloquially as a "blue hunter's moon."
It is called a hunter's moon because traditionally it was known to provide light to hunters as they used moonlight to hunt for food in preparation for winter.
"Blue" moons earn their nickname not due to the shade of the moon's color, but because a second full moon in the same month is so rare – happening only once every three years or so – or "once in a blue moon."
But if blue moons are rare, that is nothing compared to a full moon occurring on Halloween. Such an event, happening across time zones, has not happened since 1944.