Some of the brightest and swiftest shooting stars will bedazzle the night sky this month during the Orionid meteor shower, which will peak next Thursday and Friday (Oct. 20-21) and continue through early November.
NASA meteor expert Bill Cooke said the Orionid meteors are special because they are pieces of Comet 1P/Halley, commonly referred to as Halley’s Comet. This famous comet swings by Earth once every 75 to 76 years, so most people will have a chance to see it only once in their lifetime. “But every year, you can see pieces of Halley’s Comet during the Eta Aquarids [in May] and the Orionid meteor shower,” Cooke said.
The Orionid meteor shower’s intensity varies from year to year. This year, skywatchers can expect about 15 to 20 meteors per hour, but in some years, they have exceeded rates of 70 to 80 per hour, Cooke said. And while there may not be a lot of them in the sky this year, they’re still worth checking out: Orionid meteors are known for being some of the fastest and brightest, sprinting across the sky at a relative speed of about 148,000 mph (238,000 km/h). “If you blink, you might miss them,” Cooke said.
When to see them
This year’s Orionid meteors can already be seen; you have a chance to spot them any night from Oct. 2 to Nov. 7. But the best part of the show will happen between Oct. 20 and Oct. 21, during the meteor shower’s peak. Early morning, before dawn, is the best time to look for the meteors, Cooke said.
Moonlight could make the meteors a bit difficult to spot. October’s full “supermoon” will rise just a few days before the meteor shower’s peak viewing times. Meteors will streak through the sky at a rate of up to 20 per hour this year, but skywatchers can expect to see closer to 15 meteors per hour with the moonlight obstructing the view.
“A good thing about the Orionids is that they tend to either have a double peak or a flat maximum, which means that you can see good Orionid rates for two to three nights,” Cooke said. “So if you miss it one night, you can go out the next night and see them.”
Where to look
Orionid meteors are visible from anywhere on Earth and can be seen anywhere across the sky. They appear to originate in the constellation Orion, close to the bright-red star Betelgeuse.
If you find the shape of Orion the Hunter, the meteor shower’s radiant (or point of origin) will be near Orion’s sword, slightly north of his left shoulder. But don’t stare straight at this spot, Cooke said, “because meteors close to the radiant have short trails and are harder to see — so you want to look away from Orion.”
What causes the Orionids?
The Orionid meteor shower happens every year during October and November, when Earth’s orbit around the sun crosses paths with debris from Halley’s Comet. As the icy comet makes its way around the sun, it leaves behind a little trail of comet crumbs.
These tiny comet fragments — some as small as a grain of sand — are called meteoroids. When they enter Earth’s atmosphere, they become meteors. Friction from air resistance causes meteors to heat up, creating a bright, fiery trail commonly referred to as a shooting star. Most meteors disintegrate before making it to the ground. The few that do strike the Earth’s surface are called meteorites. [How Often Do Meteorites Hit the Earth?]
How to get the best view
As is the case with most nighttime skywatching events, light pollution can hinder your view of the Orionid meteor shower. The best place to be is somewhere with a dark sky, away from major cities.
Cooke recommended lying flat on your back and looking straight up at the sky. This way, you’ll be able to see more of the sky than you would if you were sitting or standing while facing just one direction.