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From: TerryMoselaol.com
Date: Fri, 19 Nov 2004 15:21:38 EST
Subject: What meteors?, ISS

Hi all,

1.  It's not often you get an email from me sent just before 7 a.m.! But I 
happened to be awake & heard the 06.30 BBC Radio Ulster News describe a "Meteor 
Storm" to be expected later tonight (Fri 19 Nov). Shortly after, one of the 
presenters did an interview with a spokesman for the Royal Astronomical Society, 
whose name I will omit, about the expected "storm". I was so perturbed at 
this that I got up & sent out the email! (They ran the headline story again on 
the main 7a.m. News.)

This was, I presume, based on a Press Release from the RAS, about the 
possibility of some unusual 'late' Leonid meteor activity. As you all know the 
Leonids come every November, usually around Nov 17. But various astronomers, 
including Dr David Asher at Armagh, had predicted the possibility of some enhanced 
activity on Nov 19/20, after the shower would normally have ended. So far so 
good - David's record on such predictions is impeccable! But neither David, nor 
any of his colleagues, described the possible level of activity as a storm! In 
fact, the predicted level is only about 10 meteors per hour! That's not even a 
decent normal annual shower level! Nor did they say it would be visible from 
UK/Ireland - the best place to see it would be much further East. In fairness, 
the RAS spokesman did refer to this.

But he did also say in the interview that there were two possible times to 
see these 'storm' meteors from here - from 9.30 to 10 p.m., and around midnight. 
It was the first of these that got my goat! The radiant will be WELL below 
our horizon even at 10 p.m., so we wouldn't see anything! Even from far Eastern 
England, the radiant won't have risen by 10 p.m. So there simply won't be any 
Leonids visible from the UK at that time. And we in Ireland are furthest away 
in the British Isles from even the remote possibility of seeing anything. If 
someone from the RAS does not realise that, there's not much hope for 
popularising astronomy!

It's loose, misleading statements like that which can get astronomers a bad 
name among the public - somebody raises expectations, people go out and observe 
and see nothing and get totally disillusioned, and don't pay any attention to 
future, realistic, predictions. 

Even at the second time mentioned, 'around midnight', the level of activity 
would be barely above the normal background rate, and would not even be noticed 
by the casual observer! At this time of year we get around 10 meteors per 
hour from the sporadic background every night! Of course you'll only see that 
rate from a very clear dark sky! And with the Leonid radiant so low, a nominal 
rate of 10 Leonids per hour would translate to about 1-2 per hour actually 
observable! 

Anyway to call a possible maximum (ZHR) rate of 10 per hour a "meteor storm" 
is grossly misleading! Perhaps the word "storm" originated with the BBC, but 
it didn't sound like it! The accepted definition of a storm is at least 1000 
meteors per hour, so 10 hardly qualifies!

And just to emphasise the difference,  we do expect a really good meteor 
shower (but not a storm) from the Geminids in December - best activity on the 
night of 13/14 December when rates might reach 80 per hour - so I hope that this 
'False Alarm' wll not put people off.

I'm glad to note that after I sent out my email this morning (which went to 
all my media contacts), the BBC stopped running the story, so maybe it was 
worth getting up so early!

To sum up: we just MIGHT see some slight activity from the Leonids, after the 
shower would normally have ended, at around, or shortly after, midnight 
tonight, but don't expect anything spectacular! In fact, the level of activity is 
expected to be so low here that I hadn't even issued an alert about it.....

(More on the Geminids closer to the time, of course!)

2. However, to compensate for the lack of Leonids, we are currently being 
favoured with the start of another series of evening passes of the ISS. As I'm 
sure you know, it appears as a bright moving star, sometimes nearly as bright as 
Jupiter, crossing the sky over a period of a few minutes, generally from West 
to East. The times vary from night to night, but you can get up to date 
predictions for your location from  For example, there's a 
good one at about 18.10 for Belfast on Saturday night: times in other areas 
will vary by up to 10 minutes.

Clear Skies,

Terry Moseley

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