Halloween celebrations may be cancelled for the most part in Toronto for 2020, but at least that means you'll be home to catch a glimpse of the rare blue moon that's set to light up the sky on the spookiest night of the year.

That's right, a Halloween full Hunter's Moon will rise above the city this Saturday night for the first time in many years, providing all the creepy ambiance needed to have a happy and haunted Halloween. 

"On average, the Moon is full on Halloween every 19 years, a period known as the Metonic cycle, used for centuries to construct luni-solar calendars and to calculate the date of Easter," according to NASA.

The last time a Halloween blue moon appeared in the sky was in 2001, according to Farmer's Almanac, but that year it was only visible in Central and Pacific time zones. 

This year, the majestic sight will be visible in all time zones around the world — a phenomenon that hasn't happened since 1944. 

"When you look at the full Moon on Halloween night, it won't appear blue in color but you'll be looking at something pretty uncommon," wrote the Farmer's Almanac of this weekend's blue moon.

"For more than half a century, whenever two full Moons appear in a single month (which happens on average every 2 1/2 to 3 years), the second full Moon is christened a 'Blue Moon.'"

On Oct. 1, for example, a full harvest moon lit up the night sky. This makes the Halloween moon the second full moon of the month, and therefore a blue moon.

Astronomers say the next time we'll get to see a 100 per cent-illuminated blue Halloween full moon will be in the years 2039, 2058, 2077, and 2096.