If you are outside just after sunset tonight, you may catch a meteor out of the corner of your eye if you are very, very lucky.
Earlier this year, scientists predicted Earth would pass through patches of dust left behind by a tiny comet known as 15P/Finlay, for the first time in late 2021.
At best this meteor shower, dubbed the Finlayids, is not likely to be a dazzler.
And it is just a prediction — albeit from some of the best comet scientists in the world — so there’s a chance it may not happen at all.
“We think we might see something, but nobody is really sure because it’s never been seen before,” says Jonti Horner, an astronomer at the University of Southern Queensland.
So what do we, and don’t we, know? Let’s take a closer look at the prediction.
Why is this the first shower from 15P/Finlay?
Meteor showers are created when the Earth passes through the debris trail laid down over years by comets and the occasional asteroid.
15P/Finlay, which hails from around Jupiter, swings around the Sun about once every six years or so.
As far as comets go it’s “far from spectacular,” Professor Horner says.
“They think the diameter of the nucleus of the dirty snowball in the middle is maybe one or 2 kilometres across.”
Sometimes when a comet gets close to the Sun, it lets off more dust than usual.
“If the meteor stream is this big broad river, these filaments are like someone floating a javelin or twig of wood down the river,” Professor Horner explains.
According to the prediction, this is the first time we are going to cross dust filaments laid down by Comet 15P/Finlay.
This comet is not very active, but we are about to go through three filaments that were created when it zipped around the Sun in 1995, 2008 and 2014.
When is the meteor shower meant to happen?
According to the calculations, there are three showers (coinciding with each of the outbursts): the first on September 28-29, and two more between October 6-7.
But they may be hard to see because they are predicted to happen mainly during the day in Australia.
“The only one of these that’s even visible to us at night at all in Australia is the first one,” Professor Horner says.
The peak — when we can expect the highest number of meteors — is predicted to occur at 6:35pm (AEST) on Wednesday (September 29).
That’s just on sunset for the eastern states, but still during the day for Central and Western Australia. However, it’s still worth looking up in the evening as the peak may be late.
“The prediction of the times are reasonably good, but they are not set in stone,” he says.
“It’s worth looking away from the times they are predicting because the unexpected can always happen.”
The next shower peaks during the day about 1:00pm (AEST) on October 6, and the third one is about 10:00am (AEST) on October 7.
“That’s why they are not so exciting for us in a way, but there is always a possibility that those timings are out by a bit,” Professor Horner says.
There is a possibility that the peaks of the meteor showers could last longer because we are encountering the stream at a very gentle angle.
“We are … almost running parallel to it, gradually grazing, rather than cutting through it directly and quickly.”
Where in the sky would I need to look?
Look about 30 to 45 degrees above the southern horizon just after sunset on September 29, and a bit further towards the east on October 6 and 7.
Predicting where in the sky it comes from is based on what direction the meteors are moving and what direction the Earth is moving.
By a quirk of fate, the northern hemisphere gets the best view of most meteor showers.
“The angle at which those paths are crossing Earth’s orbit is essentially random. But it just happens that the densest trails we are running into hit the Earth coming down from the north towards the south.”
But this meteor shower is coming up from the south, so the meteors will appear from a point in the southern sky.
It’s unclear where that point will appear, which is why the meteor shower is not currently named after a constellation.
The best bet is Ara, a small constellation between the Southern Cross and Sagittarius, aka “The Teapot”.
The further south you are, the higher in the sky Ara will be through the night.
“I think it’s likely to be from a certain patch of the sky, but there are two or three constellations there — it’s a little bit woolly,” Professor Horner says.
How many meteors might we see?
We don’t exactly know, but this isn’t going to be one of our most spectacular showers.
The rates for the first shower are predicted to be around only 13 meteors per hour if the radiant point is directly above your head (known as the zenith hourly rate, or ZHR) under dark sky conditions.
That’s great if you’re a person or penguin on Macquarie Island in the Southern Ocean, but the rest of Australia can expect to see lower rates than that.
And the further north you are, the less you will see because the radiant point will be lower to the horizon.
The ZHR is higher on October 6 and 7, but they will be harder to see during the daytime if the peak prediction is correct.
“The other thing that makes the Finlayids harder to observe is that the shower is actually encountering the Earth almost as slowly as it is possible to do so,” Professor Horner.
That means they won’t be very bright, so they will be hard to see in the twilight or daytime.
Will we get to see them again next year?
We don’t know, but probably not.
“It’s not going to be an annual shower, at least initially, because the level of dust in the stream is very low and we’re basically only clipping it,” Professor Horner says.
But we won’t really know that much about it until we actually go through the dust filaments for the first time.
Over the past 20 years, scientists have been observing meteor showers such as the Leonids — a very fast and bright shower that occurs in the northern hemisphere between 14 to 20 November — to refine their predictions.
And they’ve got pretty good at it.
Just last month, they accurately predicted the exact time and date there would be a sudden outburst of the Aurigids meteor shower.
“Because we’ve hit filaments [from its comet] in the past, we had something to work with,” Professor Horner says.
They predict another shower, the Tau Herculids, might go off next May over the western Atlantic region.
“It could yield a spectacular meteor storm — the best we’ve had in 100 or 200 years — but it’s equally likely nothing will happen.”
Didn’t see anything? Don’t worry, there are more meteor showers on the horizon
If the Finlayids turn out to be a fizzer and you’re not averse to staying up beyond midnight, there are some other meteor showers in the northern sky between now and December.
- Taurids: late September to early December. The rates of this meteor shower are very low, but the meteors are very bright. “On an average year the Earth gets more material from the Taurids than all the other showers added together, even though the rates are low, because we are passing through it for such a long period of time,” Professor Horner says.
- Orionids: peaks October 20 – 21. This shower has good rates, but the meteors are not that bright. This year the shower will coincide with the full moon, which will make seeing them tricky.
- Geminids: peaks December 14. This is by far the best shower in the southern hemisphere. It has consistently good rates and bright meteors. The moon will also be nearly full when the shower peaks, but they will still be worth a watch.
The other thing to remember, Professor Horner says, is that you may see a random shooting star at any hour of the day, any day of the year.
“Even if you went out to look at these and you didn’t see them, but you sat out for an hour or two, got your eyes used to the darkness, you might see four or five meteors an hour anyway.”
So it pays to look up. You never know, you could get lucky.Internet Explorer Channel Network