October is a good month for meteor activity, the main event being the Orionids. The Orionid meteor shower tends to start around 2 October, building slowly to a peak, which in 2020 occurs on the night of 20/21 October.
The Moon will be largely out of the way this year, leaving the night sky good and dark for meteor watching.
On the night of 20 October 2020, the 21%-lit waxing crescent Moon sets around 20:10 BST (19:10 UT) and will not interfere further on peak night.
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For more on meteor showers, read our meteor shower guide.
What is the Orionid meteor shower?
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 (see the illustration at the top of this page).
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, or short-period, 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.
When to see October’s meteor showers:
- 20/21 October for the Orionids
- 6/7 and 7/8 October for the Draconids
- 10 October for the Southern Taurids
How to see an Orionid meteor
When meteor watching, 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.
How good will the 2020 Orionid meteor shower be?
The 2020 Orionid shower is expected to produce a ZHR (zenithal hourly rate) of around 25 meteors per hour, translating into a visual rate of 4–10 meteors per hour, depending on the quality of the night sky in your location.
The peak nights of 20/21 October should produce the best results, but it’s always worth keeping an eye out over the nights before and after as the Orionid shower has been known to exhibit sub-peaks.
Other meteor showers happening in October 2020
Draconid meteor shower
The Orionids is not the only shower active during October. The Draconid meteor shower in 2020 reaches its peak on the evening of 8 October, but there is also the possibility of two short outburst peaks, one at 02:25 BST (01:25 UT) and another at 02:57 BST (01:57 UT), both on 7 October.
A bright Moon will interfere later in the night, but as the best time to view the Draconids is earlier in the evening, this should still allow a decent view.
Typically, the Draconids produce a peak ZHR of 10 meteors per hour, but short-term boosts – up to 300 meteors per hour – have been seen in recent years. They are slow moving meteors with an atmospheric entry speed of 21km/s.
Southern Taurid meteor shower
Another famous shower reaches a broad peak on 10 October. The 2020 Southern Taurid meteor shower has a peak ZHR of around 5 meteors per hour, but its broad peak persists over several days.
It’s part of the Taurid stream, its Northern Taurid counterpart reaching peak activity on 12 November 2020 with a similar ZHR.
The Taurids have shown fireball activity in the past: events caused by slightly larger than normal debris in the stream. The parent comet for the Taurids is 2P/Encke.
Pete Lawrence is an experienced meteor observer and a co-host of The Sky at Night. This guide originally appeared in the October 2020 issue of BBC Sky at Night Magazine.