What the Orionid Meteor Shower Peak Means for Your Night Sky Plans

Anyone hoping to see the Orionid meteor shower this week should plan for the early hours of Thursday, Oct. 22, when the shower peaks and a bright moon finally drops out of the sky. According to Live Science, the peak runs overnight from Wednesday, Oct. 21, into Thursday, with around 20 meteors per hour possible under a dark sky.

The BBC says viewers could spot as many as 10-20 meteors per hour if skies are clear. It also warns that the weather in the U.K. may get in the way.

What this means for your night out

The practical message from both outlets is that timing matters more than equipment. The Orionids can be seen with the naked eye, and the BBC says no binoculars or telescope are needed. Live Science adds that binoculars or a small telescope can help show more sights during peak skywatching season, but they are not required for the meteors.

The BBC advises finding a dark spot with wide open skies, away from city light pollution, and letting your eyes adjust to the dark for 20 minutes before looking up.

The moon is the main complication. Live Science reports that a 71%-illuminated waxing gibbous moon will brighten much of the night and make fainter meteors harder to see. The BBC notes that conditions should improve once the moon sets around 03:00 BST on Thursday morning. That leaves a window of darkness before dawn, which Live Science calls the best time to watch.

Where to look in the sky

The meteors appear to spread out from a point in the constellation Orion, near the red supergiant star Betelgeuse. Astronomers call this point the radiant, and it gives the shower its name. According to the BBC, Orion climbs higher in the sky to the south and then the south-west between midnight and dawn. Live Science says Orion will be high in the predawn hours.

Both outlets say there is no need to stare straight at Orion. The BBC advises looking slightly away from the radiant, where meteors are more visible. Live Science says meteors seen farther from the radiant can leave longer streaks across the sky.

The weather problem in the U.K.

The BBC says this week looks to be the wettest and windiest of the autumn so far, as a strengthening jet stream pushes low-pressure systems across the country. Wednesday looks wet and windy for many areas.

The forecaster sees a possible opening. A brief ridge of high pressure could bring clear spells to many parts of England, Wales and Northern Ireland in the second half of the night into Thursday morning. Western Scotland may also see clear skies for a time. Eastern Scotland looks cloudy and wet because of a lingering front, and the far south coast of England could see outbreaks of rain.

Why the shower happens

The Orionids are an annual shower caused by debris left behind by Halley's Comet. Live Science explains that heat from the sun makes the comet shed dust and rocky particles along its orbit each time it passes through the inner solar system. Earth crosses streams of that debris, and the particles vaporize as they hit the atmosphere.

Halley's Comet does not need to be nearby for this to happen. Live Science, citing The Planets Today, says the comet is currently beyond the orbit of Neptune. It last passed through the inner solar system in 1986 and will return in 2061.

Both outlets say the Orionids are fast, hitting the atmosphere at around 41 miles per second. Live Science gives the metric figure as 66 kilometers per second. They can produce bright streaks and fireballs. Live Science adds that they sometimes leave persistent trains, which are glowing trails that stay visible briefly after the meteor has gone.

Live Science also notes that Halley's Comet produces two meteor showers a year. Earth meets its debris in late October during the Orionids and again in early May during the Eta Aquariids.

What happens next

Cloud or a bright moon does not end the show. The BBC says the Orionids have been active for most of October, and viewers will still have chances to catch some meteors until Nov. 7, though rates will be lower than at the peak.

Sources: BBC News, Live Science