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Physicsman

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Physicsman last won the day on December 10 2016

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  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!
  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!
  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. 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!!"
  5. Cheers Rich. I store all the data on SSDs - and a 10,000 frame video comes in at 20Gb, so it soon accumulates. About 15Tb since August 2022.
  6. 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.
  7. 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!
  8. 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!
  9. 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. 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.
  10. 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!
  11. Don, Shaun - thanks for the comments. And Peter, you've been modelling longer than I have, so it's good to know that others suffer from this (almost illogical) loss of interest. As promised, a few Moon pics - I have to keep Ade happy! These are compressed Jpegs - much smaller files than the original TIFs. But they do stand a bit of enlargement. To give a sense of scale, the largest craters in these images are around 60 - 80 miles (100 - 130km) in diameter. North east area of the Moon: One of the large "seas" - Mare Serenitatis - a huge (400 miles across) lava bed.... The 60 mile wide crater Plato, with internal shadows from the mountains on its Western wall: The Caucasus Mountains and "Alpine Valley" (at upper left corner): South eastern area of the Moon - craters everywhere! Hope these are of interest. Hopefully, there may be some railway-related stuff on here later in the Spring!
  12. 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!
  13. Good evening folks (actually 1.30am). Thanks to Rich and Peter for showing interest in the thread, despite the long period of inaction. So let me explain what's been going on - aside from virtually nothing! I haven't done any work on the layout - and I mean zero - since August 2022. There IS an "on-going" project that I'd started in July 22 and this will be my primary focus IF - or should I say WHEN - I get back out there.... Basically, what happened in the months following August 22 was a "perfect storm". From converting the garage in 2020 up until that time I'd spent around 2000 hours in the Bunker. Some days I didn't mean to leave, especially when building the viaduct. Then, suddenly, my interest fell to zero. And I mean zero. In 25 years of modelling, that had never happened before. In conjunction, August 22 saw "tweaks" to my telescope set-up produce some stunning imaging results. Since that date I've had half a dozen images published in one of the main national Astronomy magazines. As a follow-up to accumulating over 20 Terabytes of data, I spent most of last summer producing a 600 page document with images and analysis. This will be updated this spring to over 1000 pages. So the two "hobbies" conflicted with devastating effect to the railway! I DO intend to start back on the layout once things warm up a bit. I have Steve Gibbons ( "Ramrig" on RMweb) to thank for re-igniting my interest. I also have 8 00 steam locos being re-gauged by a friend, and 3 SLW class 25 diesels on order. The first of these (D7599) should arrive in the next month or two. The EM locos should provide additional incentive to do something. I plan to add more scenery onto the layout as well as the scratchbuilding project. I find it pointless to pursue anything without a hundred percent commitment, so it's been a long haul back! All is well in the Bunker. Cool, but dry and everything works. On a couple of occasions I've just popped in, switched on, and run a loco and wagons around - no cleaning or anything needed. Thanks to all who've persevered with the thread. And, as I noted elsewhere on RMweb, very sad about my good friend Jonathan(R17D)'s passing last month. I hope that explains a few things. Cheers, Rich. And Peter, so good to see that your sense of humour is as good as it's always been. You made me chuckle! Best wishes to all!
  14. I'm very sad to say that Jonathan passed away on Tuesday, January 9th. I'd known him since we both worked in the Teesside area nearly 20 years ago, and he was doing some modelling work at Ormesby Hall, Middlesbrough. Jonathan was always supportive of a fellow Midland modeller - I've always modelled the S&C - and we became great friends over the years. Such a lovely, generous man. And a really good modeller. His wife Claire and family knew the inevitability of this day once his cancer "re-lapsed" last summer, but we all hoped his recent treatment might produce a solution. Jonathan will be sorely missed. RIP, my good friend. Jeff.
  15. 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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