Orionid meteor shower 2021: how and when to see it

Find out how to see the Orionid meteor shower in October 2021 with our beginners' guide.

The annual Orionid meteor shower reaches peak activity on 21 October 2021.

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With a peak zenithal hourly rate (ZHR) of 20 meteors per hour, the Orionids is a popular event to observe.

ZHR refers to the number of meteors you might expect to see in an hour under perfectly dark conditions under a clear sky.

During 2021 however, the peak occurs with a just-past-full Moon in the sky and many of the shower’s trails will be lost to its glare. As a result, the Orionid meteor shower might not live up to expectations in 2021.

Read the Countryfile guide on how to observe the Orionid meteor shower.

An Orionid meteor appears over Nantucket, US. Credit: J. Greg Hinson, MD, www.ackdoc.com / Getty Images
An Orionid meteor (left above centre) appears over Nantucket, US. Credit: J. Greg Hinson, MD, www.ackdoc.com / Getty Images

Despite the potential lack of visible Orionid meteors in 2021, the event can still make for a good excuse to get out with family and friends and look up at the night sky.

There’s plenty more to see in October, after all, as the nights get longer and darker.

You could try and observe some of our favourite autumn constellations, or read our autumn astronomy guide. Or tick off our favourite autumn binocular targets.

And as the month progresses, see if you can spot some of the targets on our Halloween astronomy list.

But if you’re really in the mood for a meteor shower in autumn, the good news is that a lower-rate shower named the Draconids, which can be seen in early October, won’t be spoiled by moonlight..

Get weekly lunar phases delivered direct to your email inbox by signing up to our e-newsletter.

For more on meteor showers, read our meteor shower guide.

What is the Orionid meteor shower?

Betelgeuse and Rigel. Credit: iStock
The Orionids’ radiant is near the star Betelgeuse in Orion. Credit: iStock

The Orionid meteor shower is so-called because its peak activity has the shower radiant in Orion.

A meteor shower’s radiant is the position in the sky from where the shower meteors appear to emanate. In this case the Orionids’ radiant is near the star Betelgeuse in Orion.

Meteor showers are typically (but not always) associated with comets. As a comet orbits the Sun, it releases dust. Earth passes through these dust streams every year and, when this happens, the number of meteor trails seen increases.

Peak activity occurs when we pass through the densest part of the stream, and from our perspective the incoming trails appear to originate from the shower radiant, which slowly moves over the duration of the shower.

The Orionids are associated with comet 1P/Halley, the first such object to be determined as a periodic comet.

Halley’s comet returns to perihelion – its closest point to the Sun, every 76 years, and was last in this position on 9 February 1986.

How to see an Orionid meteor

Even though the Orionid meteor shower is due to be somewhat washed out by the Moon in 2021, below is our evergreen meteor-observing advice.

When looking for meteor showers, comfort is key and using a garden chair, a recliner or sunbed is a good idea to prevent neck cramp.

Aim to look about 60° up in the sky. At this point, atmospheric thickness isn’t sufficient to reduce the brightness of meteor trails, but it’s sufficiently thick for an optimal number of meteors to be seen.

Also, wrap up warm. You’ll be observing in the middle of October, and standing or sitting still in an open space is sure to make things chilly. It’s important to wrap up warm even if temperatures are fairly mild at the session’s start.

Find a dark location, free from stray light, and allow about 20 minutes for your eyes to adapt to the darkness. This will help you see more stars and more meteors.

Make sure you have a clear, unobstructed view and, if possible, view in groups. This means that you’ll have more eyes on the sky to spot a meteor.

You could even take it in turns to note down meteors as others spot them, creating a scientific record of your observations by the end of the evening.

If do this, get in touch with the British Astronomical Association Meteor Section and send them your data.

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This guide originally appeared in the October 2021 issue of BBC Sky at Night Magazine.