In the spirit of spooky season, a full blue moon will shine over trick-or-treaters on Halloween this year for the first time in nearly two decades, the AccuWeather Global Weather Center said Wednesday.
A blue moon is the second full moon in a calendar month. While not actually blue in color, it often looks orange or red when near the horizon.
According to NASA, blue moons appear once every two-and-a-half years but this one is even rarer. Blue moons only shine on Halloween approximately every 19 years, with the last one appearing on Halloween night in 2001.
The rarity of blue moons is where the phrase “once in a blue moon” originates from.
In addition to the blue moon, three bright planets will also be on display Halloween night. Mars, Jupiter and Saturn will be visible in the night sky without a telescope.
Mars will be to the right of the moon and Jupiter and Saturn will appear side-by-side in the southern sky.
2020 has been an extraordinary year for eerie events.
This year, the first full moon in October, the Harvest Moon, rose on Oct. 1, though usually shining in September. And, exactly 13 days after Halloween, 2020 will see its second Friday the 13th on Nov. 13.
The next Halloween blue moon won’t happen until 2039.