A Rare Blue Moon Will Haunt the Sky on Halloween

Kelly Corbett
·2-min read

From Popular Mechanics

  • You'll be able to see a blue moon on Halloween night this year.

  • In some years, there are 13 full moons in a year instead of 12. This bonus moon is called a blue moon.

  • You won't be able to catch another blue moon on Halloween night until 2039.

While 2020 may not be the best year for travel (or even leaving the house), it has been a great year for celestial events, from witnessing a naked-eye comet soaring through the sky in July to seeing the stunning Perseids Meteor Shower in August.

Turns out a blue moon is also on the menu for this year's skies. This rare phenomenon will occur tomorrow, October 31, 2020. That’s right: a blue moon on Halloween night. Get ready for an extra creepy time.

🌌 The universe is a trip. Let's explore it together.

What is a blue moon?

In a perfect world, a blue moon would most likely mean that the moon appears blue during the night. That’s usually not the case, unfortunately. A moon isn’t considered a “blue moon” because of its color, but rather, when it occurs.

As you may already know, full moons typically occur once a month. When 13 fulls moons occur in one year instead of 12, that means you have a blue moon. (Its uncommon nature is the basis for the phrase "once in a blue moon.")

There are two types of blue moons: A full moon can be considered blue when it's the second of two full moons in a calendar month (a monthly blue moon), or when it’s the third of four full moons in a single season (a seasonal blue moon), according to Earth Sky.

While there’s a good chance October’s blue moon won’t actually appear blue for us Earth-dwellers down below, it doesn’t mean it’s completely impossible. According to timeanddate, a moon can appear blue if the atmosphere is filled with dust or smoke particles of a certain size.

Therefore, if a massive volcanic eruption occurred, that could give the moon a blueish tone. The 1980 eruption of Mt. St. Helens in the U.S., the 1983 eruption of Mt. Krakatoa in Indonesia, and the 1991 eruption of Mount Pinatubo in the Philippines have all made the moon look blue.

What type of blue moon will we see in 2020?

This year’s blue moon will be a monthly blue moon. There was a full moon on October 1 and there will be one on October 31, 2020. Because October has two full moons scheduled, the latter full moon is dubbed as the blue moon.

According to AccuWeather meteorologist Brian Lada, we won't be able to catch another blue moon on Halloween night until 2039. With that in mind, mark your calendars now.

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