Meteor season is well and truly underway, and tonight you might be able to see remnants of Halley’s Comet in a dazzling light show of shooting stars from the Orionid meteor shower.
If you were not able to spot one of the elusive Draconids earlier in the month, then the Orionids should put on a much better show. They’re fast-moving meteors which occasionally leave persistent trails, and, like the Taurids, sometimes produce bright fireballs.
The Orionids are often considered to be one of the most beautiful meteor showers of the year, and with the Moon setting early, we’re in with a good chance to see bright meteors streak across the night sky.
So, what’s the best way to maximise your chances of spotting an Orionid? What causes the Orionid meteor shower? And, when exactly should you look up to see it?
If you’d like to make the most of the longer evenings, be sure to check out our beginner’s guide to astronomy. Astrophotography expert Pete Lawrence has also put together a jam-packed guide to lunar photography, so even if you’ve only got a smartphone, you can learn to take great pictures of the Moon.
When is the Orionid meteor shower 2023?
The Orionid meteor shower peaks tonight, Saturday 21 October 2023, and in the early morning before sunrise on Sunday 22 October 2023.
The Orionid meteor shower began on 2 October 2023 and will continue until 7 November 2023.
When is the best time to see the Orionid meteor shower?
The best time to view the Orionids in 2023 will be between midnight and sunrise (which occurs at approximately 7:35am BST) on the morning of Sunday 22 October 2023. The morning before, 21 October, should also offer decent views. This applies to wherever you are in the Northern Hemisphere.
Clouds permitting, we should be offered semi-decent viewing conditions, thanks to a first-quarter Moon, which is still a week away from full. Handily, however, the Moon itself will rise at 3:15pm BST on 21 October in the UK (and 2:23pm local time in New York City, 2:02pm in Los Angeles) and set at 10:16pm BST (11.23pm local time in New York City, 11:51pm in Los Angeles) that same evening, so it won’t be around in the early morning to interfere with proceedings.
But don’t worry if you miss the peak, as Dr Minjae Kim, an astronomer from the University of Warwick explains: “You can easily catch a glimpse of this meteor shower for several days before and after its peak date on your annual calendar.”
Where to look to see the Orionids
As the name suggests, the Orionids appear to come from the constellation Orion. The radiant rises around 10:30pm BST on 21 October and is highest in the sky around 3am BST (2am UTC) on 22 October.
The easiest way to find Orion is to look for the hunter’s famous belt. There are three bright stars – Alnitak, Alnilam, and Mintaka – which form Orion’s belt and are relatively close together, almost in a straight line. Two more stars make up the hunter’s feet, and another two make up his shoulders.
Betelgeuse is one of the shoulder stars, and is distinctive thanks to its bright orange colour. If you look slightly below Orion’s belt, keen eyes may even be able to spot a fuzzy patch; the Orion Nebula. The exact radiant, is a point at the northwest corner of the constellation, just to the north of Betelgeuse.
If you're still struggling to find this in the night sky, using an app may help (check our best astronomy apps).
However, you don’t need to exclusively look towards Orion; the meteors will be visible across the whole of the sky. And by looking away from the radiant, you’ll also have the advantage of ‘foreshortening’. This is when a meteor's train can look shorter nearer the radiant because it’s angled towards us. So by looking away from the radiant, you’ll potentially be able to see ‘longer’ meteors.
How many Orionid meteors can we see?
The number of meteors we’re able to see starts to rise sharply as we approach the maximum on 21-22 October. Under a dark sky with no Moon, we can expect to see between 10-20 meteors per hour at the maximum.
The Orionids produce bright, fast meteors, and this is useful to us when viewing. They travel at speeds of up to 66km per second (a whopping 148,000 mph), which means that – weather permitting – we might be treated to glowing trains; incandescent debris fragments that persist for longer in the wake of the meteor.
Fireballs (extremely bright meteors) are also possible in this meteor shower, as the fast meteors can lead to prolonged explosions of light.
The Orionids have a broad maximum which lasts for around a week centred on the peak, so even after the 21/22 October, we’ll still have a decent chance to spot an Orionid. Just beware of the pesky Moon which begins to set later and later as we approach full on 28 October (Hunter’s Moon). After that, the number of meteors we see will begin to taper off, as we reach the tail end of the shower in early November.
What causes the Orionid meteor shower?
The Orionid meteor shower is one of a pair, the other being the Eta Aquariids in May. Both are the result of Earth ploughing through debris from Halley’s Comet, officially designated 1P/Halley.
"This meteor shower holds a special place in the annual calendar of celestial events, not only for its breath-taking beauty but also because it originates from the debris of one of the most renowned comets in history, Halley's Comet (1P/Halley),” says Kim.
Halley’s Comet is probably the most famous of all known comets, thanks to it being the first instance where astronomers understood that comets could return to our skies.
“Halley's Comet graces Earth with its presence only once every 75 to 76 years, leaving behind a trail of cosmic debris, including dust and grit, along its orbit during each pass around the Sun.”
“So, if you missed the 'once-in-a-lifetime event' of Halley’s Comet [in 1986], don't worry, this annual Orionid meteor shower offers a unique opportunity providing some compensation," says Kim.
Halley’s Comet is comprised of a crumbly mixture of volatile ices and dust and is what we call a ‘dirty snowball’ comet. It’s been travelling around the Sun for at least 16,000 years, and in this time, it’s scattered debris along its highly elliptical orbit. This orbit stretches out beyond the orbit of Neptune and will make two-and-a-bit orbits of the Sun, in the time it takes Neptune to make one.
Every time Earth’s own orbit intersects with this stream of dust – which it does twice a year – particles enter our atmosphere and disintegrate, resulting in the bright streaks we see as meteors.
Where is Halley’s comet now?
Halley’s comet is still heading away from us, having last visited our skies in April 1986. It’s currently approaching the furthest point away from Earth in its orbit around the Sun (aphelion) and has passed beyond the orbit of Neptune.
Some estimates say that it will reach aphelion in December 2023, others in 2025, but after that, it will start its long return journey back towards the inner Solar System. Conditions permitting, we’ll be able to see Halley’s Comet with the naked eye in July 2061.
What else can I see in the night sky?
If you’re looking for other targets to spot while you pass the time, then you’ll be hard-pressed to miss Venus, low on the eastern horizon just before dawn on 22 October. Currently shining as the ‘morning star’, Venus will be visible at a very bright -4.28 magnitude (the lower the number, the brighter the object), rising just after 3am in the UK.
Turn your attention towards the west, and you’ll easily be able to spot the granddaddy of the Solar System, Jupiter, in the constellation Aries. As Jupiter approaches opposition on 3 November 2023, it’s becoming a major player in the night sky. It’s above the horizon all night (rising in the East), and shining at a bright -2.74 magnitude.
If you’re in the UK and up for a challenge, then we’ve also got the added bonus of potentially spotting the International Space Station (ISS) around the same time as the Orionids peak in the early morning of 22 October. It’s fast-moving but slow enough for our human eyes to spot, as a point of light that glides across the sky.
To spot the ISS, look towards the southwest at 6:07am in the UK, and you might be able to spot it low on the horizon, just below the constellation Lepus the Hare. It will cross Canis Major at 6:09am, before heading into Hydra 6:11am. After that, the ISS will pass below Venus at 6:12am, before entering Virgo a few moments later and sinking below the horizon at 6:16am.
For other locations, to find out when the ISS will be visible near you, head over to NASA’s ‘Spot the Station’ website (spotthestation.nasa.gov). It’ll tell you exactly when the ISS will pass overhead and in which direction you'll need to look to see it.
How to maximise your chances of seeing this beautiful shower: Viewing tips
If the weather holds out for us, then the best time to view the Orionids will be either on the morning of 21 October or the morning of 22 October. The constellation Orion and the radiant rises higher into the sky as the night progresses, and is highest just before dawn. However, decent views will be on offer from around midnight, so no need to set your alarm super early.
For the best chance at spotting an Orionid, find a dark area away from light pollution and the glare of streetlights, and allow around 10-20 minutes for your eyes to adapt to the darkness. After your eyes have acclimatised, you’ll be able to see objects much more clearly.
Try not to look at other bright sources of light during this time. If you need to check your phone, it’s a good idea to use a red filter, otherwise, you’ll undo the time spent acclimatising to the darkness. A red-light torch will let you read or use reference books during this time.
Although Orionids will appear to originate from the constellation Orion, they can appear in any part of the sky, so try to get as wide a field of view in your vision as possible.
About our expert
Dr Minjae Kim is a research fellow in the astronomy and astrophysics group at the University of Warwick. He is the ESA project lead working on the dust of comet 67P/Churyumov-Gerasimenko collected by Rosetta/MIDAS, with the aim of understanding comet and dust growth in the early Solar System.
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