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Barry Fitz-Gerald

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About Barry Fitz-Gerald

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    Dorchester UK

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  1. Hello again! In reply to your first point, an impact event on the lunar surface will approximate an explosion as the kinetic energy of the impactor is released almost instantaneously - that is why most craters are round and only extremely low angle impacts producing elongate craters . As I noted above even with an impactor arriving at cosmic velocities varying from 14kms/sec up to 75kms/sec the energy released is still only in the thousands of degrees C and whilst this will vapourise, melt and shatter the target rock (an the impactor) the temperatures will NOT be in the several millions r
  2. I would agree with Vlaiv, they do not look like any artificial satellites that I have seen, which all appear as point sources with no structure - well to my eyes at least. Your objects have structure, the pair group look like slightly crumpled spheres illuminated from the top right and with the opposite side in shadow, whilst the elongate object looks like a partially eaten sausage (there is a less savoury analogy - but I will not use that one) but also appears to be illuminated from the same source as the pair. Both groups show what appears to be intrinsic colour - a shade of brown/orange but
  3. The composition of the ejecta blanket is related to the rocks present at the impact site, as it is these that are shattered, melted and vapourised. These processes will clearly alter the minerals in the rocks (by shock effects and heating) and change their physical state, but the temperatures involved are in the 1000's of degrees not the millions required by fission/fusion nuclear reactions. So nothing is made in these impact events beyond that produced by heat and shock. Also, plagioclase will only be present in the ejecta blanket of a crater if there is plagioclase present in the rocks
  4. These features are Dark Halo Craters (DHC's) - and they form where an impact excavates darker, usually mare type basalts or pyroclastic deposits from beneath a lighter surface. In this case the surface is dominated by Copernicus ejecta rich in light highland rock (a plagioclase feldspar rich rock called anorthosite which is intrinsically bright - see The Genesis Rock found on the Apollo 15 mission) and a small impact has penetrated this and produced its own ejecta blanket of a much darker nature, probably composed of pulverized mare basalts from an underlying mare surface. DHC's are good probe
  5. Yes, those are pretty impressive images - but the interpretation given by the LROC team is not the correct one I suspect. They show two impacts making up Messier A (the bottom image in your post) which they have called Impact 1 and Impact 2, with Impact 1 supposedly an older crater that already existed and was partially obliterated by Impact 2. Have a look at the image that goes with this post, it is taken from the LRO Quickmap page with the LRO Diviner Nighttime Soil Temperature layer enabled, where red is warm and yellows cooler. The temperature differences are related to the 'rockiness' of
  6. Meteors and Asteroids strike the lunar surface at all angles ranging from 90 degrees to grazing impacts. However due to their velocity which can be from say 12 to 75kms per second the effect is not like throwing a large rock at a hard surface. During the impact shockwaves are generated wich pass into the surface and through the impactor. This occurs in such a short timescale that it caused the impactor to be melted and vapourised in what is effect an explosion from a point, with no effect being carried over from the impactors trajectory. This symmetrical 'explosion' results in a circular impa
  7. Stu, Sorry to disappoint but sinuous rilles are volcanic features, no need to invoke the flow of water which has never existed in liquid form on the moon as it would immediately sublimate in the vacuum of space. Water is present but in amounts so small that it would require industrial processes to release it from the hydrated minerals which contain it or the regolith in permanently shadowed craters. Sinuous rilles were formed by flowing liquid, but this was basaltic lava at high temperature (1,200 degrees C) and very low viscosity - comparable viscosity to engine oil. Basalts are th
  8. Space weathering takes the form of meteorite and micrometeorite bombardment which occurs constantly and shatters and effectively 'sandblasts' everything on the surface, from boulders down to the smallest particle. Returned lunar samples revealed that even the smallest particles in the soil had miniature craters on them called 'zap pits' Radiation also damages rocks exposed on the surface as energetic solar and cosmic rays penetrate the minerals in the rocks and cause damage on the atomic/molecular scale. The net effect is that a rock on the lunar surface will be reduced to fine grained dust i
  9. This is a small (approximately 50m diameter) very fresh impact crater. The impactor struck the floor of the large crater Theophilus in an area where iron rich, low albedo (dark) impact melt dominates the surface. The impact excavated material which has a lower iron abundance and a higher plagioclase feldspar content, which is typical of the lunar highlands. This plagioclase rich material is not only bright due to its content (it is a light coloured mineral) but it is also bright as it is optically immature - it has not been exposed to space weathering which darkens and eventually obliterates b
  10. Just remembered - it was also sold under the brand name Sky Rover in the far east, so maybe a few turned up in Australia (https://www.astronomyalive.com.au/product/sky-rover-ult-130-ed-glass-130mm-triplet-super-apo-refractor-telescope/) The later iterations of all these Kunming Optical scopes turn up under different badges - as do most non top end telescopes so it seems. You are correct about re-sale value however, probably not as good as a 'branded' scope, but if it performs well it could have anything written on the dew shield as far as I am concerned.
  11. This looks identical in every way - including the case - to telescopes that were sold under the OSTARA name in the UK. They appeared in the most unusual outlets and also in on-line vendor ad's. I strongly suspect they are made by the same Chinese company that supplied the Orion Eon's and the Altair Astro Wave 130 that was reviewed in Sky at Night in 2013 as they appear superficially to be identical apart from the badge on the dewshield. Of course these suppliers can specify what specs they require from the manufactures such as glass, number of baffles and so on and so the clones sold under di
  12. Dorchester in Dorset? If so send me a PM - I am also in Dorchester!
  13. Thanks - silly me! I would like to buy it in that case - I am new to SGL, so how do we go about the transaction? Barry
  14. Hi, Is this EP still available, and do yu have an idea of what postage to the UK would be? Thanks, Barry.
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