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TonyM
New Member
18 Posts
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 Posted -
09/07/2008
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14:29
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By popular request here are some metoer showers to look out for with approximate dates (the actual dates vary slightly from year to year):-
The Persieds around August 12th
The Orionids around October 2nd - November 7th
The Leonids around November 17th plus or minus a week.
Here is a link to a list of meteor showers http://en.wikipedia.org/wiki/List_of_meteor_showers
(many will not be visible to us because they are not bright enough, occur during our day time or are visible from the Southern hemisphere).
The "Right Ascension" and "Declination" give you their positions but off the top of my head I can't translate that into directions (they are a bit like longitude and latitude but relating to the sky.
Edited by - TonyM on 09/07/2008 2:33:36 PM
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panbiker
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Posted - 09/07/2008 : 22:42
Geminids 12th December for 3 days
Quantratids January 3rd
Are some of the more productive showers having a potential of just over 100 per hour for the former and up to 130 per hour for the Quantratids shower. You need a nice crisp clear winters night to see the best displays. Try to get away from light pollution as much as possible.
The showers are named after the constellations they appear from so you can judge the general direction to watch. I used to take my children out when they were younger to see one of "the greatest shows on earth" all totally free of course and well worth the effort if you get a good night. Some of the trails can track right across the sky and last five or six seconds, depending on the size of the meteor skirting or entering the atmosphere.
Radio Amateurs use the trails as a propagation method, you can bounce signals off the trails during their brief existence and depending on the angle that your signal hits the ionised trail, achieve vast distances of communication on the VHF bands. Very brief, but contacts can be built up piece by piece on successive meteor scatter trails.
Ian  |
Stanley
Local Historian & Old Fart
36804 Posts
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Posted - 10/07/2008 : 06:12
I seem to remember something called the 'Heavyside Layer' from the days when these things really mattered. I remember being in Harold Bailey's radio shack in Denton one Sundat over 60 years ago and being amazed that he could talk to a bloke in Australia. Best meteor shower I ever saw was in Minnesota, less light pollution I suppose. very impressive sught and it would have been in August I think.
Stanley Challenger Graham
Barlick View
stanley at barnoldswick.freeserve.co.uk |
panbiker
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Posted - 10/07/2008 : 22:57
quote:
Stanley wrote:
I seem to remember something called the 'Heavyside Layer' from the days when these things really mattered.
Still does matter Stanley. The Heaviside Layer or more correctly the Kennelly-Heaviside Layer is the E layer of the Ionosphere. It is named after the two scientists who first put forward their theories of it's existence almost simultaneously although they were working independently of one another.
The Ionosphere is responsible for the propagation of radio signals (up to around 30MHz). Signals at these frequencies bounce between the earth and the Ionosphere the height of this layer is governed by the solar wind. During daytime the Ionosphere is compressed by the solar wind closer to the earth. At night it is dragged further away by the solar wind. This is why we hear more radio signals from distant stations at night. The signals propagate over the horizon as they bounce between the Ionosphere and the earth. The higher the layer is, the further the signals propagate.
Other factors such as increased sunspot activity can also effect the Ionosphere. Increased radiation from sunspot activity bombards the Ionosphere and excites Oxygen and Nitrogen molecules in the gasseous layers which glow with the various colours of the visible spectrum during Auroral events. The excited molecules align with the magnetic flux lines eminating from the poles, causing the coloured ribbon and striation displays that are visible during an Auroral display.
Higher frequency radio signals are propagated in the lower, Tropospheric layers of the atmosphere and are subject to the high and low pressure effects that govern our weather. High Pressure or a sudden change in pressure from high to low or vice versa coupled with pressure ducting effects can propagate normal "line of sight" radio communication to hundreds or on occassion, thousands of miles under exceptional conditions.
It's all fascinating stuff, propagation effects was a major part of my interest as a Radio Amateur. I used to operate low power on the VHF bands and build my own antennas to get maximum power gain from low power. You can reach anywhere in the world if you pick the right frequency on the lower HF bands at various times of the day but you get quite a buz when you can talk to a guy in Siberia on 1 watt of power at 144MHz from Barlick!
Edited by - panbiker on 10/07/2008 23:08:14
Ian |
Stanley
Local Historian & Old Fart
36804 Posts
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Posted - 11/07/2008 : 07:53
I can share your enthusiasm. I have a picture in my mind's eye of that dusty room over a garage in Denton nearly 70 years ago as I watched Harold Bailey adjust dials and make contact with Australia. I suppose we were naive then, I'd never seen a TV and everything was a miracle. I can remember the big dial with a lovely fine needle on our Echo 8 valve Superhet radio set as I twiddled my way round to names like Hilversum, Droitwich Moscow and even Berlin! This was during the war. Magic..... We take so much for granted nowadays.
Stanley Challenger Graham
Barlick View
stanley at barnoldswick.freeserve.co.uk |
Julie in Norfolk
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Posted - 11/07/2008 : 08:21
Enter Tony Hancock.......
Measure with a micrometer.
Mark with a pencil.
Cut with an axe. |
Tizer
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Posted - 11/07/2008 : 10:10
These OGFB forums amaze me with the depth of knowledge and intensity of enthusiasm of the participants - wonderful!
Talking astronomy and radio reminds me - I hope you've all seen the 2001 Australian film "The Dish"? A remote Australian antenna, populated by quirky characters, plays a key role in the first Apollo moon landing. It's great fun!
http://www.imdb.com/title/tt0205873/
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panbiker
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Posted - 11/07/2008 : 14:53
Agree Tizer, a good film and based on truth. Fantastic achievement but very much "seat of the pants" in many areas.
Ian |
panbiker
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Posted - 11/08/2009 : 17:20
Perseids meteor shower at the moment (since July) , tonight through to dawn is the peak although the shower will continue further into August. Not the best conditions here at the moment but the shower could bring as many as 80 meteors per hour.
Early in the evening the shower will radiate from the Nort East sky but as Perseids rises higher as the night progresses the trails will be visible from all directions. Worth a look if the sky clears especially if you can observe away from light pollution.
Edited by - panbiker on 11/08/2009 17:27:27
Ian |
Stanley
Local Historian & Old Fart
36804 Posts
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Posted - 12/08/2009 : 08:10
Not a lot of chance of cloud cover lifting the way the weather is at the moment.
Stanley Challenger Graham
Barlick View
stanley at barnoldswick.freeserve.co.uk |
Tizer
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Posted - 12/08/2009 : 12:46
The moon may be too bright, some reports say. But let's be optimistic - a little cloud might come over the moon!
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panbiker
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Posted - 12/08/2009 : 16:59
Wedy and Doc and those others that live a little out of the way of the worst of the light pollution will stand the best chance. I bet it's nice and dark on the hillside where Wendy lives. Letcliffe is'nt bad locallyt if you go to the back of the park, seen some good shows up there when my kids were small.
Ian |
frankwilk
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Posted - 12/08/2009 : 19:51
Looks promising tonight, clear sky at the moment.
Frank Wilkinson Once Navy Always Navy |
Tizer
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Posted - 12/08/2009 : 19:58
Wall to wall cloud in south Somerset so far.
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wendyf
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Posted - 12/08/2009 : 20:20
Getting cloudier all the time, but if it clears again I will try and stay awake long enough to go out into the dark and watch.
Wendy
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Stanley
Local Historian & Old Fart
36804 Posts
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Posted - 13/08/2009 : 08:03
Went out and had a look but too much cloud.
Stanley Challenger Graham
Barlick View
stanley at barnoldswick.freeserve.co.uk |
Meteor Showers
