There’s no shortage of meteor activity this December. As well as the Geminids, which arguably look set to be the most beautiful shower of the year, we also have the possibility that a ‘lost shower’ will return, the Andromedids. And it may return as a meteor storm.
If that’s not enough, there’s also the possibility that we may see a new, as yet unnamed, meteor shower from comet 46P/Wirtanen between 10-12 December.
When to see the 'lost' Andromedids shower 2023
The expected peak for this lost shower will be on the evening of 2 December 2023 in the UK and US. In the UK, this peak will be at 7pm – the Moon will be below the horizon at this time, giving you around 90 minutes of excellent observing conditions. (The 77 per cent illuminated waning gibbous Moon rises at 8:33pm as viewed from London.)
In what could be a spectacular return to form, some astronomers have predicted that this year, 2023, may be a meteor ‘storm year’ for the Andromedids (also known as the December phi Cassiopeiids).
It’s possible that we could see as many as 200 meteors per hour on the evening of 2 Dec. If so, this would surpass even the generous helping of Geminids, which are expected to produce 120 – 150 meteors per hour when they peak between 12–15 December.
The British Astronomical Association says that although the peak is predicted for 2 December, it's still important to observe on 1 and 3 December.
The American Meteor Association also notes that the display will favour the evening skies of Europe, northern Africa, and western Asia, as the sun sets around three to four hours after the potential outburst in the US.
If it happens, the meteors from this meteor storm are likely to be slow, around 16km per second, and faint, so dark sky sites have a definite advantage. And it won’t be an annual occurrence, either – so vigilance is a must.
Why is it called a “lost shower”?
The Andromedids saw activity in the 19th century, but this has since died down (in older texts, you might see them referred to as ‘Bielids’). So much so, the Andromedids were classified as a ‘lost stream’ by Sir Alfred Charles Bernard Lovell in 1954.
More on their history below.
Where do the Andromedids come from?
Like other meteor showers, the Andromedids – if they occur – are created when Earth’s orbit intersects with a stream of dust and debris previously shed by a comet (or asteroid, as is the case with the Quadrantids in January or the Geminids) as it orbits the Sun.
As the dust and other small bits of debris interact with Earth’s atmosphere, usually at high speeds, they burn up due to friction with the air. This results in streaks of light we see as meteors, or shooting stars.
Most, but not all, meteor showers are annual events, occurring at the same time every year, as the Earth crosses the debris paths from these specific comets and asteroids. This Andromedid meteor shower, for example, is not an annual event.
In the case of the elusive Andromedids, the source of this shower comes from a broad stream of dust left behind by the disintegration of Comet 3D/Biela, or Biela’s Comet.
The missing Biela’s Comet
We’ve known about Biela’s Comet since 1772, when it was just below naked-eye visibility. In its day, Biela’s Comet was a periodic comet, with a 6.6-year orbit around the Sun.
After studying several apparitions of the comet in the following decades, astronomers at the time suspected that the comet had begun to break up. It was unexpectedly observed in two pieces in 1846, then failed to show up for its 1852 apparition. After this, it continued to disintegrate and was never conclusively seen again, and was designated a ‘lost comet’. (This is why there is a ‘D’ in the comet’s official designation of 3D/Biela; it stands for ‘defunct’.)
Then, in 1872, in place of the comet’s expected return, a major meteor storm occurred on 27 November, with hourly rates peaking at a whopping 3,000 meteors. A meteor storm also occurred in 1885, and it was surmised that debris from the break-up caused these impressive showers.
Meteor storms were observed regularly towards the end of the 19th century (the 18-hundreds), but began to taper off into the start of the 20th century before fading into much of a non-event. This was likely down to the gravitational pull of one of the planets displacing the orbit of the debris field so that it no longer intersected with that of the Earth.
The meteor shower returns - could it be a meteor storm this year?
In 2001, the Near-Earth Asteroid Tracking program (NEAT) discovered a comet (2001 J1 NEAT) that bore similarities to Biela’s Comet, prompting many to speculate that a surviving fragment of the lost comet had been found. This is not confirmed, however, and astronomers are still debating whether they are one and the same.
Fast forward to 3–5 December 2011, and multiple radar stations in Canada detected around 50 meteors per hour, appearing to originate from near the constellation Cassiopeia.
Subsequent analysis by Paul Weigert et al published in The Astronomical Journal determined that the source of this 2011 meteor shower was indeed Biela’s Comet. The astronomers concluded that the 2011 shower was “typical of the ‘classical’ Andromedids of the early 1800s, whose radiant was actually in Cassiopeia.”
Based on their modelling from the 2011 burst of activity, Weigert’s team have predicted another strong outburst for 2023. It’s probable that, if it occurs, the meteor shower will be associated with dust the comet shed in 1649, long before its break-up.
Where to look to see the meteor storm
If the storm happens, the meteors will be visible over the whole sky, so try and take in as much of the sky as possible. However, as the meteors will appear to originate from one location (the ‘radiant’), this is a useful way to tell your Andromedid from your Geminid.
For this shower, when viewed from the UK, the radiant will be high overhead at around 7pm GMT. It will most likely either be in the northern constellation of Pegasus, which is easy to spot thanks to the familiar asterism the Great Square of Pegasus, or the neighbouring Andromeda. The American Meteor Association notes that the radiant will likely cover a large part of the sky, but emphasises that as these are predictions only – so timings and locations may differ on the night.
For help locating Pegasus (or any constellation), using an app may help (we’ve rounded up the best astronomy apps) as you can simply point your phone at the sky and the app will tell you what’s what.
How to maximise your chances of spotting meteors from Biela’s Comet
We’ll have a fairly bright Moon to contend with later in the evening on Saturday 2 December (77 per cent illuminated waning gibbous Moon), so finding somewhere away from other bright lights (for example, streetlights) will help minimise light pollution.
If you can, try to take in as much of the sky as possible in your field of vision. Further away from the radiant, and you’ll be able to see meteors with longer trains – which are easier to spot. Nearer to the radiant, the meteors will leave shorter trails because they are angled more towards us (this effect is called ‘foreshortening’).
For much of the UK, the weather is looking clear (but cold) so wrap up warm, and find somewhere in the dark to let your eyes adjust for 10-20 minutes. A recliner is a great way to enjoy meteor showers, and if you have a tally counter to hand, you can keep track of the number of meteors you see.
Fingers crossed!
About our expert, Dr Darren Baskill
Dr Darren Baskill is an outreach officer and lecturer in the department of physics and astronomy at the University of Sussex. He previously lectured at the Royal Observatory Greenwich, where he also initiated the annual Astronomy Photographer of the Year competition.
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