Catch October’s harvest moon as you wait for the rare Halloween blue moon

Take a break from the world’s chaos Friday night and head out to see the almost-full moon. The nighttime spectacle is visible in all parts of the US, weather permitting, astronomy educator and former planetarium director Jeffrey Hunt says. This full moon is romantically called the “harvest moon,” as its the full moon closest to the start of fall.

“The moon is only full for one night (Oct. 1), although it looks full on the nights before and after the official full phase,” Hunt said. “Before and after, it is 98 percent full.”

The harvest moon won’t look as full after Friday night, but it’s just a preview for the second full moon of the month,  which happens on Halloween. That full moon is called the blue moon, because it’s the second full moon of the same month. And in a rare treat, the 2020 Halloween full moon will be visible to the entire world, rather than just parts of it, for the first time since World War II.

“When I was teaching, my high school students thought a full moon occurred every Halloween,” Hunt told me. Not quite, though pop culture decorations sure make it seem that way. The last Halloween full moon visible around the globe came in 1944, he said. He’s written about the event on his web site, When the Curves Line Up. There was a Halloween full moon for some locations in 1955, but that didn’t include western North America and the western Pacific, Hunt says.

While this year’s Halloween full moon will be visible in all parts of the globe, that doesn’t mean every single citizen will have a view. Residents across both North America and South America will see it, as will India, all of Europe and much of Asia. But while Western Australians will see it, those in the central and eastern parts of the country will not. 

Know time zones well? “Every time zone has it except those east of (GMT) +8 time zones if they have daylight time, or (GMT) +9 with no daylight time,” Hunt says.

Want to see the Halloween full moon? It’s so bright at the full phase it doesn’t matter if you’re in a crowded city or out on the farm. And you don’t need pricey equipment.

“Walk outside, and take a look,” Hunt says. 

Don’t be surprised, though, if you snap a Halloween moon shot with your phone and the photo doesn’t match what you saw.

“When the moon is photographed with a smartphone the results can be disappointing,” Hunt admits. “A telephoto attachment will help make the moon larger.” 

If you’re too busy watching horror movies (or doing whatever the coronavirus equivalent of trick-or-treating is), you’ll have to wait until 2039 for another global full moon.

“Of course, full moons occur in October during the intervening years, just not on Halloween,” Hunt says. And a Halloween full moon may appear in your region before then. It just won’t be seen around the world.