Earth's orbit crosses the comet's path each year, and our planet is now passing through this cosmic belt of dust.
(See an interactive map of the solar system.)
As they enter Earth's atmosphere at some 42 miles (67 kilometers) a second, the fragments superheat the air molecules along their path, and the energy makes those molecules glow with incandescent light.
Though they put on a good show, the comet remnants are surprisingly tiny.
"Most of the things that make a nice, good visual meteor are the size of a grain of sand," said Scott Sandford, an astrophysicist at NASA's Ames Research Center at Moffett Field, California.
"This is a wide stream, so it will take a couple of days to completely pass through," Sandford added.
People all over Earth will have a chance to see the meteors, he noted.
"Meteors are hitting all the time," Sandford said, "even in daylight, although it's too bright to see them."
Meteors streak across the sky some 50 to 70 miles (80 to 110 kilometers) aloft, but they are easily visible from the ground.
To Earthly observers, the trajectories of the Orionids seem to point back to the constellation Orion—but the objects may appear anywhere in the sky.
First-time observers need no special equipment. Experts suggest simply gazing toward the sky's darkest region, avoiding as much artificial light as possible, because it dims the fainter meteors.
The most challenging aspect of enjoying the shower may be weather-related—especially in northern latitudes.
Observing the Orionids means being outside during the chilliest part of the night.
"Meteor watching is one of the coldest activities known to man," MacRobert cautioned. "So bundle up."
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