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Perseids Meteor Shower 2016

August sees the return of the most reliable meteor shower of the year; the Perseids, with rates of shooting stars possibly increasing to over 100 per hour under perfect conditions.

Read my previous blog post Meteor Showers: The What, How, Where, When, Why for general advice on how best to observe meteor showers.

A shooting star – otherwise known as a meteor – is a tiny piece of space dust that burns up in our atmosphere, forming a bright, brief streak of light in the sky. Many people have never seen a shooting star, and think they’re rare events, but given dark skies you can expect to see a few every hour on a clear night. From cities, under light polluted skies, you can’t see most of the faint ones, and so only the rarer bright ones are visible.

However at regular times each year the Earth moves through thick clouds of space dust – left behind by comets – and we get a dramatically increased rate of meteors. On the night of 12/13 August we’ll pass through the densest part of a dust cloud left behind by Comet 109P/Swift-Tuttle, and will see the rate of meteors increase by a factor of 20!

You can begin watching for Perseid meteors now, and the shower will last until late-August, but the peak of the shower occurs overnight on 12/13 August 2016, which means that the nights on either side of this will be best for meteorwatching.

Location of the Perseids Radiant at 0001 on 13 August

Location of the Perseids Radiant at 0001 on 13 August

The best time of night to watch the meteor shower is from around 2200 onwards on 12 August, once the radiant, the point from where the meteors appear to originate, rises above the horizon. However the moon will be in the sky until after midnight, and will interfere slightly for observers in dark sites. The later you observe the higher the radiant will be, and the more meteors you’ll see.

The number of meteors that you will observe every hour depends on a number of factors:
•the density of the dust cloud that the Earth is moving through, that is causing the shower in the first place;
•the height above the horizon of the radiant of the shower, the point from which the meteors appear to radiate;
•the fraction of your sky that is obscured by cloud;
•the darkness of your sky, measured using naked-eye limiting magnitude, a measure of the faintest object you can see.

This year the Perseid meteor shower has an expected zenith hourly rate (ZHR) of around 150. This is the number of meteors that you can expect to see if the radiant is directly overhead (the point in the sky called the zenith), and you are observing under a cloudless sky with no trace of light pollution.

However conditions are rarely that perfect. In the UK, for example, the radiant of the shower will not be at the zenith; it will be around 30° above the horizon at 2200, 40° high at midnight, and 50° high at 0200.

Assuming a clear night, the other factor is the limiting magnitude of the sky, a measure of the faintest object you can see. Man-made light pollution will be an issue for most people. From suburbia the limiting magnitude of the sky is ~4.5 (around 500 stars visible), so you will only be able to see meteors that are at least this bright; the fainter ones wouldn’t be visible through the orange glow. In a big city centre your limiting magnitude might be ~3 (only around 50 stars visible); in a very dark site like Galloway Forest Dark Sky Park the limiting magnitude is ~6.5 (many thousands of stars visible), limited only by the sensitivity of your eye. So in most cases it’s best to try and get somewhere nice and dark, away from man-made light pollution.

The calculation that you need to make in order to determine your actual hourly rate is:

Actual Hourly Rate = (ZHR x sin(h))/((1/(1-k)) x 2^(6.5-m)) where

h = the height of the radiant above the horizon

k = fraction of the sky covered in cloud

m = limiting magnitude

Let’s plug the numbers in for the Persieds 2016.

ZHR = 150 at the peak, say.

h = 30° at 2200, 40° at 0000, 50° at 0200, 65° at 0400

k = 0 (let’s hope!)

m = 6.5 (if you’re observing under skies free from light pollution)

So your actual hourly rate under clear dark skies is

(150 x sin(30))/((1/(1-0) x 2^(6.5-6.5) = 75 meteors per hour at 2200
(150 x sin(40))/((1/(1-0) x 2^(6.5-6.5) = 96 meteors per hour at 0000
(150 x sin(50))/((1/(1-0) x 2^(6.5-6.5) = 115 meteors per hour at 0200
(150 x sin(65))/((1/(1-0) x 2^(6.5-6.5) = 135 meteors per hour at 0400

Remember though that these numbers apply only to the peak of the Perseid occuring at these times. If the peak happens at 0400 on 13 August (and we’re not sure exactly when it’ll occur) then you might see 135 meteors per hour, but “only” 75 per hour if the peak occurs at 2200 on 12 August.

Remember that these rates are for perfectly dark skies. If you live in suburbia then divide these numbers by 4 or 5; if you live in a bright city divide these numbers by 10. Take home message: get somewhere dark!

It is worthwhile having a look on the days leading up to the peak, when the numbers of meteors will be gradually increasing towards this rate.

Live in or near Glasgow? Come and join me for the Perseids #Meteorwatch at Whitelee Wind Farm!

Lyrids Meteor Shower 2015

April 18, 2015 3 comments

UPDATE 24/04/15 Now that we’re past the peak it looks like the Lyrids meteor shower performed as expected. Reports from the Society for Popular Astronomy suggest that plenty of meteors were seen over the UK.lyr2015overview

A wider survey made by volunteers submitting data to the International Meteor Organisation shows that a peak with ZHW=18 occurred more or less on cue around midnight on 22/23 April, with a possible second several hours later around 0700UT where the rate if anything was a little higher, with ZHR=22.

 

Over the next week one of spring’s best meteor showers will start to put on a show. The Lyrids meteor shower peaks overnight on the night of 22/23 April 2015, and should be best around midnight.

lyrid-meteor-shower-592x309

It’s quite hard to predict when exactly the peak will occur, and indeed you’ll still see some Lyrid meteors on the nights either side of the peak, so whenever you’ve got clear dark skies between now and 25 April it’s worth gazing skywards (isn’t it always?) in the hope that you’ll see a shooting star.

Why is the Lyrids Meteor Shower Happening This Week?

Meteor showers like the Lyrids happen when the Earth passes through a cloud of dust in space, These clouds are left behind by comets as they orbit the Sun, and the cometary cast-offs burn up in our atmosphere causing lots of bright streaks of light which we call meteors, or shooting stars. On any clear dark night you should see a few shooting stars, as random bits of space dust burn up overhead, but on the nights around the peak of a meteor shower, when the Earth is passing through a dense cloud of comet-dust, the rates can dramatically increase.

How Many Lyrids Will I See? There are a few ways you can maximise your chances of seeing some Lyrids (see The What, How, Where, When and Why of Meteor Showers) but the best way is to get somewhere dark, like one of the UK’s International Dark Sky Places. On the peak of the Lyrids meteor shower, under ideal conditions, you might see around 18 meteors per hour.

The peak of this particular shower doesn’t last very long, and so the rate on either side of the peak might be quite a bit less. Nonetheless it’ll still be well above the background rate of meteors. However the Lyrids occasionally surprises us and puts on a much better show. Back in 1982 there was a short-lived burst of Lyrid activity that saw the rate increase from 18 to 90. The same thing could happen this year: you never know until you look!

Ideal Conditions It’s the “ideal conditions” clause above that’ll reduce the rate from this maximum of 18. Ideal conditions are: perfectly clear skies; perfectly dark skies, free of light pollution; and the meteor shower radiant (the point where they all appear to emanate from) sitting directly overhead. The Lyrids’ radiant will be around 30° above the horizon at midnight, when the peak is meant to occur, but you can begin your meteorwatch as soon as it gets dark enough. You’ll then have until the sky brightens again pre-dawn. . The number of meteors that you will observe every hour depends on a number of factors:

  • the density of the cloud of dust that the Earth is moving through, that is causing the shower in the first place;
  • the height above the horizon of the radiant of the shower, the point from which the meteors appear to radiate;
  • the fraction of your sky that is obscured by cloud;
  • the naked-eye limiting magnitude of the sky, that is a measure of the faintest object you can see.

Crunching the Numbers The Lyrids meteor shower has a maximum zenith hourly rate (ZHR) of  around 18. This is the number of meteors that you can expect to see if the radiant is directly overhead (the point in the sky called the zenith), and you are observing under a cloudless sky with no trace of light pollution.

However conditions are rarely perfect. In the UK, for example, the radiant of the shower will not be at the zenith; it will be around 20° above the horizon at 2200, 30° above the horizon at 0000, 50° at 0200, to a maximum height of 70° pre-dawn.

Assuming a clear night, the other factor is the limiting magnitude of the sky, a measure of the faintest object you can see. Man-made light pollution will be an issue for most people. From suburbia the limiting magnitude of the sky is ~4.5 (around 500 stars visible), so you will only be able to see meteors that are at least this bright; the fainter ones wouldn’t be visible through the orange glow. In a big city centre your limiting magnitude might be ~3 (only around 50 stars visible); in a very dark site like Galloway Forest Dark Sky Park the limiting magnitude is ~6.5 (many thousands of stars visible), limited only by the sensitivity of your eye. So in most cases it’s best to try and get somewhere nice and dark, away from man-made light pollution.

The calculation that you need to make in order to determine your actual hourly rate is:

Actual Hourly Rate = (ZHR x sin(h))/((1/(1-k)) x 2^(6.5-m))

where h = the height of the radiant above the horizon

k = fraction of the sky covered in cloud

m = limiting magnitude

Let’s plug the numbers in for the Lyrids 2015.

ZHR = 18 (maximum) h = 30° at 0000 (assuming the maximum occurs at midnight; it might not) k = 0 (let’s hope!) m = 6.5 (if you get somewhere really dark)

So your actual hourly rate under clear dark skies is (18 x sin(30))/((1/(1-0) x 2^(6.5-6.5) = 9 meteors per hour If you’re observing in suburbia you need to divide this by around 4, and in bright cities by 10! Nonetheless, even in a city you’ll see a few Lyrids over the course of the night.

Orionids Meteor Shower 2014

October 9, 2014 Leave a comment

October sees a fine meteor shower, the Orionids, grace our skies. While not reaching the maximum rates of one of the Big Three Meteor Showers (Perseids, Geminids, and Quadrantids), this month’s shower is still impressive, coinciding as it does this year with the new moon, meaning dark skies and lots of meteors for those who can get out of towns and cities.

Orionids Meteor Shower

Orionids

See: Meteor Showers: The What, How, Where, When, Why 

All meteor showers happen as the Earth passes through a cloud of dust left behind by comets (or in rare cases asteroids). The Orionids is associated with the most famous of all comets, Halley’s Comet, which orbits the Sun every 75.3 years.

The best time of night to watch the Orionids meteor shower is from local midnight onwards, once the radiant (the point from where the meteors appear to originate) rises well above the horizon. The maximum rate for this shower is due to occur on 21 October 2014, but unlike the big three meteor showers the Orionids peak is very broad, lasting several days rather than several hours, and so it’s worth watching on any night for a few days either side of the peak.

The ZHR of the Orionids during 2012, from imo.net

The ZHR of the Orionids 2012, from imo.net

Compare this chart with that for the Perseids meteor shower peak, which is much narrower (although because the Perseids is a much more active shower the ZHR stays high – above 20 – for roughly the same amount of time!):

Perseids 2013 Rate, from imo.net

The ZHR of the Perseids 2013, from imo.net

The number of meteors that you will observe every hour depends on a number of factors:

  • the density of the cloud of dust that the Earth is moving through, that is causing the shower in the first place;
  • the height above the horizon of the radiant of the shower, the point from which the meteors appear to radiate;
  • the fraction of your sky that is obscured by cloud;
  • the naked-eye limiting magnitude of the sky, that is a measure of the faintest object you can see.

The Orionids meteor shower has a maximum zenith hourly rate (ZHR) of  around 25 (sometimes the ZHR can be higher, up to 40, sometimes even 70, but that isn’t expected this year). This is the number of meteors that you can expect to see if the radiant is directly overhead (the point in the sky called the zenith), and you are observing under a cloudless sky with no trace of light pollution.

However conditions are rarely perfect. In the UK, for example, the radiant of the shower will not be at the zenith; it will be around 15° above the horizon at midnight, 30° above the horizon at 2am, 45° at 4am, and reaching a maximum height of 50° due south before dawn

Assuming a clear night, the other factor is the limiting magnitude of the sky, a measure of the faintest object you can see. Man-made light pollution will be an issue for most people. From suburbia the limiting magnitude of the sky is ~4.5 (around 500 stars visible), so you will only be able to see meteors that are at least this bright; the fainter ones wouldn’t be visible through the orange glow. In a big city centre your limiting magnitude might be ~3 (only around 50 stars visible); in a very dark site like Galloway Forest Dark Sky Park the limiting magnitude is ~6.5 (many thousands of stars visible), limited only by the sensitivity of your eye. So in most cases it’s best to try and get somewhere nice and dark, away from man-made light pollution.

The calculation that you need to make in order to determine your actual hourly rate is:

Actual Hourly Rate = (ZHR x sin(h))/((1/(1-k)) x 2^(6.5-m)) where

h = the height of the radiant above the horizon

k = fraction of the sky covered in cloud

m = limiting magnitude

Let’s plug the numbers in for the Orionids 2014.

ZHR = 25 (maximum)

h = 15° at 0001, 30° at 0200, 45° at 0400

k = 0 (let’s hope!)

m = 6.5 (if you get somewhere really dark!)

So your actual hourly rate under clear dark skies is

(25 x sin(15))/((1/(1-0) x 2^(6.5-6.5) = 6.5 meteors per hour at 0001
(25 x sin(30))/((1/(1-0) x 2^(6.5-6.5) = 12.5 meteors per hour at 0200
(25 x sin(40))/((1/(1-0) x 2^(6.5-6.5) = 17.7 meteors per hour at 0400

If you’re observing in suburbia you need to divide these numbers by around 4, and in bright cities by 10!

Remember though that unlike other meteor showers where the peak lasts only a few hours these rates for the Orionids can last days, so any time you’re outside at night it’s worth looking up!

*UT = Universal Time = GMT, so for UK times (BST) add one hour to these

After the Peak: How Long Does a Meteor Shower Last?

August 13, 2014 Leave a comment

I had a question on Twitter asking whether it was worth while looking out for any Perseid meteors tonight after the shower peaked yesterday.

While individual meteors are short blink-and-you’ll-miss-them events, meteor showers themselves last many days, sometimes weeks. The rate of meteor activity builds up in the days before the peak, and tails off afterwards. The peak itself lasts a few hours, maybe a day or so for some broad-peaked showers.

Take a look at this graph of activity for the Perseids meteor shower 2013:

Perseids 2013 Rate (from imo.net)

Perseids 2013 Rate (from IMO.net)

The number of meteors per hour under ideal conditions (known as the ZHR, the Zenith Hourly Rate) built up to around 20 meteors//hour during the month before the peak. The rate started to increase around 9 Aug, doubling to 40 meteors//hour around 11 Aug, before tripling again to 120 meteors//hour around 13 Aug at the peak. The drop off was quicker, but even for the two days after the peak the rate was still above 20 meteors//hour.

So even in the days after the peak of the Perseids rates of meteors stat well above the background rate, at least 4 or 5 times that for a couple of nights.

The Night Sky in May 2014

May 2, 2014 3 comments

This month sees a glut of amazing stargazing sights in the night sky, even as the days lengthen towards summer.

Saturn, image by Kenneth Crawford and Michael A. Mayda

Saturn as it might look through a large telescope, image by Kenneth Crawford and Michael A. Mayda

Saturn is coming to opposition this month (10 May) meaning it shines in the sky all night long throughout the month. A small telescope (even a pair of binoculars on a tripod) will show Saturn’s beautiful rings and one of its moons.

Mars is even brighter than Saturn, shining a soft orange colour in the constellation of Virgo, near the bright star Spica.

Jupiter is still an evening object although it sets in the west around 1am.

There’s the possibility of a spectacular new meteor shower on 23/34 May as the Earth passes through the dust trail of comet 209P/Linear.

And May sees the start of the noctilucent cloud season, where these elusive high-altitude begin to shine in deep twilight.

Full moon this month is on 14 May, when the Moon will sit near Saturn.

Lyrids Meteor Shower 2014

April 16, 2014 3 comments

UPDATE: the peak of this year’s Lyrids is expected at 1700 UT on 22 April, so for UK meteorwatchers the best time is pre-dawn on 22 April or after midnight on 23 April. Via @popastro

Starting tonight and peaking next week on 22/23 April 2014 is our spring season’s best meteor shower, the Lyrids. It’s not nearly as dramatic as the Big Three meteor showers – the Perseids in mid-August, the Geminids in mid-December, and the Quadrantids in early January –  but dedicated meteorwatchers will catch glimpses of plenty of shooting stars overnight around or after midnight on 21/22 or 22/23 April.

Meteors

Meteors

The peak rate (more correctly the Zenith Hourly Rate) of the Lyrids is around 20 meteors per hour, but that’s under ideal conditions: 100% clear skies, zero light pollution, and the radiant (the point at which the meteors appear to emerge from) at the zenith (directly overhead). In the nights leading up to the peak you can still expect to see a few but the ZHR is much lower, around 5 meteors per hour.

So how many Lyrids can we expect to see from the UK next week at the peak? To work this out we’ll have to make some assumptions, and then crunch some numbers.

Let’s assume clear skies at least. Then we’ll assume that the peak will fall either some time between dusk on 21 April and dawn on 22 April or some time between dusk on 22 April and dawn on 23 April (currently the suggestion is that it’ll be pre-dawn on 22 April, but it’s worth watching out on both nights). Finally we’ll assume that the ZHR at the peak will be around 20.

The only limiting factors then are (a) the height of the radiant above the horizon, which changes as Lyra rises in the east, climbing high in the south by dawn; and (b) the light pollution

Time Height of Radiant* Hourly rate if peak occurs at this time
2200 21 or 22 April 18° 6
2300 21 or 22 April 25° 8
0000 21 or 22 April 32° 11
0100 22 or 23 April 40° 13
0200 22 or 23 April 49° 15
0300 22 or 23 April 57° 17
0400 22 or 23 April 65° 18**
0500 23 April 71° 19**

* This is based on my observing location in Glasgow, but it’ll only be a few degrees out .
** The last quarter Moon rises around 0330 and so will create enough light pollution to significantly reduce these numbers.

Location Limiting Magnitude Divide above hourly rates by…
Bright Urban 3.5 8
Urban 4 6
Bright Suburban 4.5 4
Suburban 5 3
Rural 6 1.5
Truly Dark 6.5 1

These graphs of previous years show the how the Lyrids activity rate increases and decreases with time centred round a peak on 22 or 23 April:

Lyrids Activity 2011

Lyrids Activity 2011

lyr2012overview

Lyrids Activity 2012

lyr2013overview

Lyrids Activity 2013

Meteor Showers: The What, How, Where, When, Why

April 16, 2014 Leave a comment

What is a meteor shower?

A meteor shower is a display of meteors (or shooting stars) during which you see lots of them in the space of just a few hours. Meteor showers occurs around the same time each year, and during the peak of the showers meteor rates increase from just a few an hour (the background rate that you’ll see on any clear, dark night) up to maybe 100 or 200 meteors every hour for observers in the perfect location viewing the most active showers.

How can I observe a meteor shower?

You don’t need any special equipment to observe a meteor shower; just your eyes. Try and get as far from city lights as possible (out into the countryside if you can, or into a local park if not), and get comfortable. You might want to bring a reclining deck chair with you, as that makes meteorwatching much more civilised! Just lie back and take in as much of the sky as possible. If you’re lucky enough to see a good display of meteors, you might see as many as one a minute, maybe more!

Where should I look?

Meteors streak across the whole sky, so you don’t need to look in any specific direction, but of course if you’ve got a tall building or tree that’s blocking the view, or a streetlight nearby that’s a bit glare-y, then put these to your back. Meteors in one shower all appear to streak from the same point in the sky (called the radiant), which sits in a specific constellation  (which is how meteor showers get their names). However you don’t need to be facing the radiant as the meteors can appear anywhere in the sky.

When do meteor showers happen?

There are many meteors showers every year, occurring regularly on the same days. The International Meteor Organisation (IMO) have a good calendar of the year’s showers, and you can find plenty more information just by googling “meteor showers 2014”, for example. Some of the very best meteor showers are: the Perseids (occurring in mid-August); the Geminids (occurring in mid-December); and the Quadrantids (occurring in early January). These showers can produce rates of up to 100 shooting stars per hour. One thing to bear in mind is that if the moon is in the sky and is anything other than a thin crescent its light will drown out many of the fainter meteors, so make sure you go meteor watching when the moon is as new as possible.

Why do meteor showers happen?

Meteors are tiny bits of space dust streaking through our atmosphere. These motes of dust float about in space and as the Earth orbits the Sun it hoovers them up. Sometimes the Earth passes through a particularly dense clump of dust, and we get lots of meteors, in a meteor shower. These clumps of dust are left behind by comets as the orbit the Sun, their streaking tails leaving behind a trail of tiny rock particles. For example, the comet that left behind the space-rocks that we’ll see in the Perseids meteor shower is called Swift-Tuttle, after the two astronomers that discovered it in 1862.

A New Meteor Shower for 2014: The Camelopardalids

January 9, 2014 Leave a comment

UPDATE: See below

This year sees a brand new meteor shower possibly gracing our night skies, on 24 May 2014.

Meteor showers occur when the Earth passes through a cloud of dust left behind by a comet. These clouds hang in space in the same place, and so meteor showers occur at the same time every year as the Earth revisits them.

But every so often a new comet comes along and creates a cloud of dust where none existed before. In the case of this anticipated shower the comet that left the cloud behind goes by the name of 209P/Linear. It was discovered in 2004 and passed near the sun in 2009, and will do so again this year in early May.

Current predictions are that the Earth will pass through the cloud of dust left by 209P/Linear on 24 May 2014. Quite how many shooting stars will be visible is unknown, but given that this is a fresh cloud of dust that hasn’t been “used up” before in previous meteor showers, we might expect a good display.

Stargazers in North America are probably best suited to see it, but in the UK it’s still worth looking out for. More accurate information regarding timings will become available nearer the time, but regardless of when exactly the Earth passes through the dust stargazers in the UK will have to wait until the sky is dark. It never gets truly dark in the UK in late May except in the south, and the Channel Islands, but the best time is between 0000 and 0200.

And where to look in the sky? As with all meteor showers it doesn’t matter where you look; the shooting stars streak across the sky in all directions. However if you trace the trails back they will all converge at the same part of the sky, called the radiant. Meteor showers are named after their radiants (e.g. the Perseids emerge from Perseus, and the Geminids from Gemini) and this new shower will appear to emanate from the dim constellation of Camelopardalis*, so they’ll be known as the Camelopardalids! Just flows off the tongue…

* Camelopard comes from the romanised Greek words for “camel” and “leopard”, and is the name for a giraffe, which the Greeks thought were part camel, part leopard!

UPDATE: The International Meteor Organisation repeats the need for caution in predicting how good this meteor shower might be:

[M]uch is unknown about this comet, including its dust productivity and even its precise orbit. Consequently, while tentative proposals have been made that ZHRs at best could reach 100+, perhaps up to storm proportions… these are far from certain. The strongest activity could be short lived too, lasting perhaps between a few minutes to a fraction of an hour only. In addition, the number of dust trails involved means there may be more than one peak, and that others could happen outside the “key hour” period, so observers at suitable locations are urged to be vigilant for as long as possible to either side of the predicted event to record whatever takes place. Remember, there are no guarantees in meteor astronomy!

They suggest that independent calculations show that the peak of activity (which might be very narrow, see above) will fall some time around 0700-0740UT (0800-0840BST) Saturday 24 May which obviously means that UK observers will miss the peak (US meteorwatchers will be perfectly placed).

However it is still worthwhile keeping an eye out during the darkest part of the night on the nights of 23/24 and 24/25 May in case there are multiple peaks, or the main peak is broad.

We just don’t know yet what is going to happen with this meteor shower: it might fizzle out to nothing, or it might reach storm levels, meaning hundreds of shooting stars per hour. Good luck!

Leonids Meteor Shower 2012

November 15, 2012 3 comments

One of the year’s regular meteor showers, the Leonids, happens this weekend, peaking at around 0930 on 17 November 2012. It (usually*) isn’t one of the very active showers (such as the Perseids, Geminids or Quadrantids), with the maximum rate in a normal year between 10-20 meteors per hour in perfect conditions.

The peak of the Leonids is quite broad, lasting several days, so between now and early next week it’s worth looking up to see if you can catch a glimpse of any shooting stars. The best time to view the Leonids shower is in the pre-dawn hours, but any time after 11pm on Thursday through to Tuesday night should mean you’ll see at least a few meteors.

How to see the Leonids Meteor Shower

1. Find somewhere dark with as little light pollution as possible. The countryside is best, but if you’re stuck in a city try and get away from as many lights as possible.
2. Bring a reclining deck chair. Standing outside looking up for long stretches of time gets uncomfortable.
3. Bring a blanket. It gets VERY cold outside at night in November.
4. Position yourself under your blanket on your reclining deck chair so that you take in as much of the sky as possible. Although the meteors all appear to radiate out of the constellation of Leo in the SE there’s no need to specifically face this direction as the meteors will streak across any part of the sky.
5. Wait. The rate of this shower isn’t very high, so you might only see one every five or ten minutes, maybe less often than that, so patience is a virtue.

* every 33 years the Leonids meteor shower turns into a meteor storm, in which the rates dramatically increase by a factor or 50 or more, up to perhaps several thousand meteors per hour. This regularity is due to the nature of the origin of the dust that causes these meteors. It comes from the tail of a comet, Comet Temple-Tuttle, which orbits the Sun once every 33 years. This means that the dust trail left behind by the comet – and subsequently hoovered up by the Earth to make a meteor shower at the same time every year – is refreshed every 33 years, resulting in a spike of activity for a few years afterward each pass of the comet. The comet last renewed the trail in 1998, and so the years 1999, 2001 and 2002 were all spectacular years for the Leonids, with storm rates peaking at 3000 Leonids per hour. I was lucky enough to see all of these showers, the most memorable being 2002 where in the space of just two hours under half-cloudy skies on the outskirts of Glasgow I saw over 300 shooting stars.

The Fireball of 21 September 2012

September 22, 2012 4 comments

Did you see it? Plenty of UK-based stargazers did; a huge, bright, long-lasting fireball streaked through the sky last night, 21 September, at 2255BST (2155UT).


The fireball was caught on meteorlog’s meteor cam

I saw it as I was driving home from a stargazing trip to Loch Tay in the Highlands of Scotland. The first glimpse I caught was behind some trees, and I clearly saw the very bright (estimated magnitude -5), yellow fragments of a space rock that was disintegrating as it burned up in our atmosphere. It was traveling westwards from the SW, and look to be about 40° above the horizon. I lost sight of it as I drove, but once I’d turned a bend in the road, a full ten seconds later, I caught the last few fragments burning it.

Straight away I pulled over and tweeted to see if anyone else had seen in, and very soon a flood of observations came in. The team at the Kielder Observatory actually had a group of people up observing, who all saw it.

Mike Alexander, who runs the Galloway Astronomy Centre, had a group of guests out stargazing then too, and they also saw it, but even better they heard it!

By the time I got home, around 0030BST this morning, only an hour and a half after it happened, there were reports of it on BBC Radio 4, with people all over the northern UK and Ireland reporting the same thing, a disintegrating fireball burning through the night sky for around 20 or 30 seconds.

By the time I woke up this morning it had made it onto BBC News.

So what was it?

A few people suggested that it might have been man-made space debris, an old satellite burning up as it de-orbits, but this isn’t the case, for a couple of reasons. First it was traveling east to west, and satellites don’t orbit in that direction. Secondly, Mike (above) reported hearing a sonic boom approx 150 seconds after it faded. Both of these observations point to the fact that it was a large chunk of space rock, a meteor. When meteors are as bright as this one we call them fireballs.

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