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Physicsman

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Posts posted by Physicsman

  1. Evening folks. Quick pop-in to see if there were any comments.

     

    Ade, there are huge positive reasons to site a radio telescope on the far side of the Moon, effectively screened from all the radio and microwave rubbish generated on Earth. But in terms of practicality and cost, it won't happen on a worthwhile scale for a long time.

     

    Relay satellites in lunar orbit can easily provide a link from lunar far side to Earth.

     

    Steve, glad you are enjoying the "rebirth" of the thread. And Rich, until it warms up sufficiently to make working in the Bunker a pleasant proposition, I'll not be out there. The Bunker is heavily insulated, but at this time of the year I can't justify heating the place for several hours - especially with the current rip-off electricity charges!

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  2. I don't know - give 'em a bit of encouragement and the boys get carried away....

     

    Lol!

     

    Seriously, although this is supposed to be a railway layout thread, there's no chance of any layout work from me until after Easter. So you're welcome to ask questions on the Moon and - as I'll pop-in every 2-3 days - I'll try and answer them (or at least give an opinion).

     

    I (again) have to say that it's good to be back on here and your response has certainly encouraged me to think more about the layout.

     

    And who knows - in the next 4-6 weeks I may even have some EM steamers to test on Gill Head!

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  3. Mac, thanks for your comment on the Gill Head thread.

     

    And many congrats for the progress you are making on this excellent layout. I've always modelled 00, then EM, but your work here is a very good advertisement for the benefits of N. Really good work.

  4. 41 minutes ago, AdeMoore said:

    Really interesting, learning a lot from the above.

    Thanks for taking the time to explain it Jeff.

    I didn’t realise we were always looking at the same side of the moon!

    So presumably if you want to photograph the hidden sides you can only do that from space?

    or have I miss read?

     

    Evening Ade.

     

    Burning the midnight oil, I see!

     

    The same side of the Moon always faces the Earth. However, the Moon appears to "wobble" in its monthly journey round the Earth (actually, Earth and Moon orbit their common centre of gravity, but as the Earth is 81 times more massive than the Moon, the CofG is inside the Earth and it appears to us that the Moon moves round us and Earth stands still). This wobble or "libration" means that we can sometimes see around the edges and over a period of time 59% of the Moon's surface is visible from Earth.

     

    It wasn't until 1959 that the far side was first photographed - from space ( by the Soviet probe Lunik 3). Since then, the entire surface of the Moon has been mapped in very fine detail.

     

    And just to clarify. During the course of a month (full moon to full moon is around 29 days), every part of the Moon, front and back, gets about 14.5 days of sunlight (then 14.5 days of darkness, etc.).

     

    There is no "dark side of the Moon".

     

    Brings to mind the Pink Floyd line: "There is no dark side of the Moon....as a matter of fact, it's all dark!!"

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  5. Rich, here's a brief answer to your imaging question.

     

    If you refer to the first or second images further up this page....

     

    Each of these is actually a mosaic of 6 separate pictures, merged together. Each component picture is made from 1000 separate "frames". So the top two pics are effectively a stack of 6000 separate images.

     

    For each picture I take, in effect, 10000 photos using my planetary camera working at 80 frames per second (I've got a couple of others that I use at around 110fps, but they are wider field). So imaging the area chosen takes about 10000/80 = 125 seconds. I then shift the telescope slightly to an adjacent area and repeat. In this case I did 6 adjacent areas.

     

    From each set of 10,000 pics, I choose the best 1,000 (10%). The 6 lots of 1,000 are then merged/composited to produce a final image. This can then be contrast adjusted, but I make as few adjustments to the basic data as I can. My aim is to produce as good a rendition of what I see through the telescope/on the laptop screen as I can.

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  6. 3 hours ago, Andrew P said:

    I have learnt so much in the last half hour. 👍 truly absorbing, and I can relate to your fascination Jeff, @Physicsman 

     

     

    I did try to read it all to my Good Lady, but was told to SHUT UP,  at this time in the morning.🤪

     

    I always knew Dee had a modicum of good sense!

     

    I mean, all that gobbledegook I've put on here!!

     

    Glad to hear that some of it made sense. I could write about this stuff for hours. And the practical part is the best - outside taking the data, even if your "whats-its" are being frozen off!

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  7. John, sorry, I meant to answer the NASA stuff question.

     

    Diffraction, the re-directing of waves when they pass through a gap - such as light into a telescope - fundamentally limits the detail we can see. Even the largest telescopes on Earth or in Earth orbit can't see details on the Moon smaller than around 100 metres. And that's under perfect conditions. 

     

    So a lunar module is completely invisible from Earth. However, satellites such as the Lunar Reconnaisance Orbiter (LRO) have imaged all the Apollo landing sites from low lunar orbit. The lander with its shadow, tracks created by the rovers etc are very clearly visible. However, the conspiracy theorists just claim this is all fake. Complete idiots!

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  8. Blimey!!

     

    I only looked on here as my Hotmail informed me that someone had sent me a PM. There's a fully-fledged astronomy course-worth of questions here! I'll try my best to give some "ball park" estimates to some of them.

     

    Impactor sizes - it all depends on the speed of impact, as well as the size of the object. The image, below, shows a picture of a near Full Moon with the "left eye" of the Man in the Moon circled in yellow. This is the "Mare Imbrium" - it's about 1100km (700 miles) across. Around 4.2 billion years ago an asteroid, estimated at around 200-300km across, hit the Moon travelling at around 60,000mph (100000km/h). This impact gouged out the Imbrium area and, over 200-300 million years it gradually filled with lava to look similar to it does today. I did a quick estimate of the mass of the asteroid - it would be around 1000 million million tonnes.

     

    Jpeg14.0dDecember07202222.52UTF800MA21GcropGcur2stitch25Paint.jpg.fd9959021609b189a4e8d830232b86f1.jpg

     

    A typical large lunar crater of around 100km diameter would need an impactor around 10 miles (16km) across. These would have been thousands of times more common than the Imbrium asteroid - this is about the size of the dinosaur-wipe-out asteroid from 64 million years ago.

     

    Steve, the Moon's rotation is "tidally locked" - it makes one rotation relative to the Sun in the time it rotates once round the Earth. So it always keeps the same side towards us. The large basins - such as Imbrium - are visible to the naked eye, but individual craters require a telescope.

     

    Yes, the Apollo missions left behind prism reflectors as part of the "ALSEP" package. A laser pulse from Earth is reflected off the reflector and part of the beam returns to Earth. The time it takes to go there-and-back is measured and the distance to the Moon calculated - laser light travels at the speed of light. The Moon is moving away from the Earth by around 3 to 4cm a year. The Moon's gravity exerts a pull on the Earth and can move water in the oceans (one cause of tides). This "sloshing" slows down the rotation of the Earth - our days are getting longer. The angular momentum of the Earth-Moon system remains approximately constant so to compensate for a slowing Earth, the Moon's orbit has to increase - it moves away.

     

    I'll do another batch of "woffle" tomorrow - time for my coffee!! (Rich, I'll outline the "photo" method I use).

     

    Thanks for asking - remember, my answers are generalities, not definitive.

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  9. Hi Andy.

     

    Good question about the Moon crater shape and thanks to "Tortuga" for providing a good response.

     

    For many years the majority of astronomers considered the Moon's craters to be of volcanic origin, like the calderas of shield volcanoes - because of the circular shape. This idea was prevalent in Europe, though many in the US pointed out the difference in scale on the Moon. Many lunar craters are over 100 miles in diameter, and the "hole" at the summit of volcanoes rarely exceeds one mile.

     

    Obvious though this was, the volcanic idea persisted. People wondered how incoming impactors (large lumps of rock, some travelling at over 50,000mph and massing thousands of tons) hitting the Moon at various angles could produce a circular shape. We now know the complete obliteration of the impactor is effectively an exploding "bomb" acting from a point - with some explosions billions of times more powerful than Hiroshima. So, whatever direction the rock hits, a circular depression (crater) is produced.

     

    For craters over around 20 miles across, the expanding shock wave (as in an earthquake) causes a rebound of material at the centre. Many larger craters have mountain groups - "central peaks" - in the middle.

     

    The Earth was also subjected to the same intense bombardment as the Moon. Most of this occurred over 4 billion years ago. Some impacts still occur today, but only relatively small objects, most of which disintegrate as they pass through the atmosphere. The crater record of the Earth has largely been wiped out over time because of the weathering effects of the atmosphere, oceans etc. And the Earth is two thirds covered in water - the Moon has no atmosphere and the bare surface retains the impact record.

     

    Fundamentally, the circular shape of lunar craters is because of the equi-directional nature of the energy release/explosions no matter what direction the impact happens.

     

    To put things into perspective, the shape and origin of the Moon's craters has only been "settled" since the late 1940s, with Apollo data confirming the idea. Then again, the Earth's tectonic plate features - fundamental to explaining much of the Earth's surface - has only been confirmed since the middle of the 20th century.

     

    Our understanding of planetary bodies has come a long way in the last century, with plenty more to learn!

     

    And Andy - I used good old Imperial units since you hate metric!!

     

    Apologies to go on here.....barely scraping the surface. I hope the pictures are enjoyable, whatever the science behind them!

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  10. I used to (seemingly) spend half my day in the Bunker, or on here. I can understand why after reading all your posts on this page.

     

    I can't promise to visit frequently at the moment but can I, AGAIN, thank you for your posts. A real "welcome back" from all of you. And Peter, Gene Cernan has always been a hero of mine, following Apollo 10 and 17 (read the excellent "Last Man in the Moon" book by Cernan and Don Davis). Must admit, Steve's "photo" isn't quite how I remember him!

     

    Ade, I'll get a few Moon pics on here over the weekend.

     

    Jay, Rich, Steve (Gill Head too cloudy for an observatory!), John - your comments only help to boost my enthusiasm to start modelling again in the next few months.

     

    As well as the re-gauged locos, there's a cattle dock, scenery and the (barely started) project to get on with.

     

    Please feel free to add further comments. Thanks (yet) again!

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  11. With the deepest of regret, I have to report that Jonathan passed away on Tuesday, January 9, after his long fight with cancer.

     

    A lovely, generous man and a really good modeller (see his Derwent Spa thread).

     

    He'll be deeply missed by his wife Claire, family and friends.

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  12. Well now, I wondered if there'd been any reaction to my last post and I look in here to find a great batch of comments!

     

    Thank you very much, gents. Your comments and support are very heartening.

     

    Had to laugh at Peter's comment - Jeffus Stargazeus (sounds like a Roman Emperor) doesn't usually hibernate from railways at any time, but over the last 3 months I've literally needed the time to process the enormous quantities of imaging data I've accumulated.

    I'm going to have to get more organised in the spring - otherwise I'll never get all the tasks done. That's assuming, of course, that our wonderful UK weather allows me to take more data!

     

    Andy, it's ridiculous that it's over 8 years since that Bacup visit. I've still got a collection of pics and, like you, enjoyed myself intensely playing (shunting) wagons.

     

    Jonathan - yes, another S&C journey is a very good idea.

     

    Shaun, John, George - glad I'm not the only one suffering from a dose of Slowus Mojous.....it's quite painful and unfamiliar. Maybe we're all just getting old!!

     

    Right, I'll have another look in during the next few days. The offer of images is still available to any who'd like them - I just need a proper, non-RMweb email addy (eg. Hotmail, gmail etc).

     

    Thanks again for your support.

     

    Jeff.

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  13. Morning folks (I'm writing this at 1.15am as I listen to a selection of classic 70s songs in the background....)

     

    I thought it was about time that I reported on the state of affairs at Gill Head.

     

    Nothing has been done in the Bunker since my last report around 6 weeks ago. I've been into the Bunker and checked that everything is ok, which it is. I've not been heating the place, but all seems dry, no condensation or insect-infestation problems. Everything just waiting for work to re-commence....

     

    I've had no real surge of interest in going in and starting again - CURRENTLY, that is. It's now 5 months since my last bit of work - it's around 2006 since a hiatus like this has happened. BUT, there are factors that will undoubtedly kick-start Gill Head work, probably from Easter onwards:

     

    It'll warm up in there!

     

    Steve Gibbons (Ramrig) has been painting a collection of figures for me - engine and road crew. They are beautifully done and deserve a place on a WORKING layout!

     

    I've had 2 SLW class 25s on order since July 2021 and these should appear at some stage this year. They'll need some exercise!

     

    At sometime in the next 6 months a collection of steam locos (6-8, including at least one 9F, Black 5, Jubilee, Brit, 4F etc) is heading off to be re-gauged - so something other than diesels to look forward to.

     

    And finally, just time is likely to set things in motion again. Running a few locos over the viaduct might fire the imagination.

     

    I've visited RMweb sporadically over the last few months, and this Gill Head thread hardly at all. Yes, I feel a bit guilty about grinding to a halt. I've also, for that reason chosen NOT to post any astro stuff on here, as I thought it a bit inappropriate given the lack of railway work.

     

    If anyone would like a few moon images, from the last 3 months, then PM me with a "proper" email address. I'll send you some images via my Hotmail.

     

    Thanks for reading.

     

    Jeff.

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  14. On 05/12/2022 at 17:33, lambiedg said:

    This is ground control to major Jeff

    your circuit’s dead is something wrong?


    David (obviously not Bowie)

     

    Hi David.

     

    Thanks for your witty comment, especially relevant as I've always been a huge Bowie fan. And thanks to those who've been interested enough to check out the thread over the last few weeks.

     

    If I tell you that the parts of the  "ongoing" project (started in late July) are in the same place as they were 10 weeks ago you'll get the idea of what has(n't) been done.

     

    I've never lost interest like this since I returned to "serious" modelling over 12 years ago. Doesn't worry me, though, as my astrophotography has gone ballistic during this time - over 1000Gb of data in the last 6 days alone. My philosophy is that I'll return to work in the Bunker when my enthusiasm level surges - which it WILL at some stage in the next few months.

     

    I have regular chats with Steve Gibbons ("ramrig" on here) and between us (he's an excellent modeller) we'll raise our mutual mojos (ooh, err) and get cracking again. I DO have landscaping plans in place in my mind - other than "the project" that's "underway", so there's tons to do when I restart.

     

    Apologies for delays in my replies. If I visit RMweb twice a week these days that's pushing it.

     

    I hope everyone that looks on here is having success with their on-going projects. If I get chance I'll put a couple of recent moon pics on here at some stage!

     

    Jeff.

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  15. On 22/10/2022 at 14:14, MarshLane said:

    Hi Jeff,
    Sorry to hear your interest level has ebbed, I am sure it will return tho.  I haven't been on rmWeb much recently, other things making calls on time unfortunately.  Still we plod on as and when we can dont we!

     

    Enjoy the astroturf .. no thats different stuff .. astro photography - Thats what I meant!

     

    Rich

     

    Thanks Rich.

     

    I can only recall a "loss of interest" happening once previously, and that was over ten years ago. If I hadn't been "distracted" by my imaging activities then I'm sure I'd still be pounding along in the Bunker.

     

    Never mind. As you well know, always better to wait for the return of genuine enthusiasm rather than bodging-up a half-hearted effort.

     

    It seems that a lot of people are spending less time on the hobby at the moment. Good luck with your own efforts!

     

    Jeff

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  16. On 20/10/2022 at 10:24, Peter Kazmierczak said:

    It's Westbury, "BW".

     

    Jeff, you'll be proud of me as I've actually stated to do some modelling again...
    It's in the "Layout topics" section under Shardlow.

     

    Well done, Peter.

     

    I had a look through your new thread. Some good improvisation with the old boards and a nice map of the setting.

     

    As I've said, I'm hardly on here at the moment but I'll keep glancing over at Shardlow when I'm here. And do keep your moon-themed pics coming - quite atmospheric and relevant to 2 of my main interests.

     

    Jeff

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  17. Morning Ade.

     

    I've nothing to report as far as work on Gill Head is concerned. I've been into the Bunker a few times over the last week but just for a "lookaround" and to clear some future ideas in my head.

     

    The on-going project sits in many pieces, exactly as it was a month ago. Not quite the timing I had planned but in addition to my low level of current interest in things railway, there are other tasks filling my time... astro imaging being foremost (400Gb of data yesterday - almost a laptop's worth in one night!)

     

    I'm grateful for your continued interest. Please keep checking in - my interest level will surge overnight, at some point!

     

    Jeff.

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  18. Hi Guys,

     

    Very sorry for the intermittent "service" but I'm hardly on here at all at the moment.

     

    Jonathan, hope your S&C odysseys are going well, along with your treatment.

     

    Rob, it's a strange experience not to feel the urge to go into the Bunker in a daily basis. I've plenty of things to do, other than my ongoing project - vegetation along the roadsides, for instance, but right now my enthusiasm is very much elsewhere.

     

    Steve, the swarms of satellites - and there are noticeably more than there used to be - don't interfere with my moon and planetary work, though they could be a pain in the ar5e if I was photographing nebulae and galaxies!

     

    I'm resisting posting more moon stuff as people, quite rightly, will look on here for modelling work! :-)

     

    Jeff

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  19. My first visit to the thread for over 3 weeks.

     

    No further modelling has been done in this time, though I plan to go into the Bunker for a couple of hours on Wednesday. I'm part-way through a project but I'll not show anything until it's been completed, which at the present rate will take a while.

     

    I managed 5 consecutive early morning Moon imaging sessions from Sept 13 - 17 inclusive. The data generated - nearly a Terabyte - took me a week to process. To put it in context - a decent Jpeg image on here might be 5Mb. In 5 nights imaging I collected around 200,000 times as much data....

     

    Thanks to those who continue to look in on here. But it's a shock for nothing to be happening after nearly 2 years continuous progress. The ongoing project WILL enhance the whole project, though, once completed (and btw, it's nothing large-scale!)

     

    I'll keep you all updated when it's possible to do so.

     

    Jeff

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  20. 2 hours ago, peach james said:

    I know that our fearless leader had a bit of a run in with him, but I’d feel a bit remiss not to link, 

    as he was active in here at one point,

     

    James

     

    James, thanks for the sad news.

     

    Rob was, indeed, a very prolific poster on the original KL thread. So much so that I even included a Rob "sub-index" within my main thread index.

     

    His posting habits did cause problems with the powers-that-be, but the way he dealt with his severe disabilities was remarkable.

     

    Jeff

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  21. Evening Ade.

     

    I'm glad you're enjoying the imaging interlude during the modelling hiatus. A while back I felt a bit guilty about doing this kind of thing. But a considerable number of thread-followers expressed a genuine interest in the space-related stuff, so it's been a regular for at least the last 5 years.

     

    I haven't had a pause in modelling since the start of Gill Head, so it's a nice change on here. Besides, I have to say that a lot of the larger layout threads are often filled with pages of woffle, so I've no regrets. For an innovative hybridised thread look no further than Clive Mortimore's entertaining Sheffield Exchange thread which blends modelling and a wide-ranging music input!

     

     

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