Wednesday night's full moon will look like an orange jack-o-lantern rising from the east at dusk, said Jack Horkheimer, executive director of the Miami Space Transit Planetarium.
It will appear orange at the horizon because it is seen through denser layers of the earth's atmosphere. Adding to the effect, the moon's tilt at this time of the year makes the "man in the moon" particularly visible.
Some astronomers believe jack-o-lantern carving was inspired by the rising, orange October moon, said Horkheimer, writer and host of PBS's nationally syndicated Star Gazer series for 25 years.
To make the superstitious even more jittery, a constellation associated with the some end-of-the-world beliefs will also be at the top of Wednesday night's sky.
The Seven Sisters constellation, which looks like a small cluster of grapes, has long been a signal for the time of year to honor the dead -- such as All Saints Day, November 1.
According to myth, the Seven Sisters constellation is at its highest point in the sky during a great calamity, possibly the biblical flood or the sinking of Atlantis. The Aztecs and Mayans believed it would be overhead at midnight on the night the world comes to an end, Horkheimer said.
The Seven Sisters and the full moon will both be directly overhead at midnight, he said.
"It's just very nifty because it will be a very bright full moon and when it's up high like that, it will just flood the landscape with a lovely bright light," said Horkheimer.
Technically, the moment the moon will be at its fullest is 12:41 a.m. EST Thursday, but the moon will look virtually full when trick or treaters are out in force late Wednesday.