A rare blue moon will rise on Halloween this month — here's what to expect.

The spooky season is finally here, bringing pumpkins, candy corn, and colorful fall foliage with it. While this year’s Halloween celebrations might look a little different because of the coronavirus pandemic, a rare Halloween blue moon will light up the sky on Oct. 31. As if 2020 wasn’t crazy enough, a combination of rare lunar events will make this Halloween extra-special. A full moon occurs on Halloween every 18 to 19 years, and a blue moon only happens every two and a half to three years, according to Farmers’ Almanac, so this combination is a really rare event.

Here’s everything you need to know about 2020’s rare Halloween blue moon.

What is a blue moon?

You’ve probably heard the phrase “once in a blue moon” to describe something that rarely happens, but do you know how that phrase came to be? “Blue moon” is the name given to the second full moon in a calendar month. According to NASA, there are about 29.5 days between full moons, so it’s pretty unusual that you’d be able to see two full moons in a month. In fact, a blue moon only occurs every two and a half to three years. This year will have 13 full moons, and this October, the first full moon — also known as the “Harvest Moon” — will rise on the first of the month, and a rare Halloween blue moon will occur on the 31st.

Are blue moons actually blue? 

It’s a common misconception that blue moons are named for their hue. Most blue moons look like your standard full moon, so don’t expect to spot a cobalt-colored satellite this Oct. 31. While Halloween’s full moon will likely appear in its usual gray color, the moon has “turned blue” in the past. Volcanic eruptions and forest fires can give the moon a bluish tint, thanks to the ash and smoke released into the air, according to NASA.

When is the next blue moon?

The next blue moon will occur in almost three years on Aug. 31, 2023. You don't need any special equipment to spot these rare moons — just hope for clear skies so you get a great view of Earth's satellite.

Elizabeth Rhodes is an associate digital editor at Travel + Leisure. Follow her adventures on Instagram at @elizabetheverywhere