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S2

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About S2

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  1. I've got an old (but still very good) 11x80 Fullerscope binos, and increasingly I'm using them in preference to my 102 mm refractor. I do like them, but I've started thinking about finding a more powerful pair (i.e. more magnification). Angled binos would also be a big plus, stopping strain in my neck during longer sessions. From <a href="http://stargazerslounge.com/observing-binoculars/143366-miyauchi-20-77-a.html">this post</a> tetenterre and neilm discussed the Miyauchi 20x77, and I thought it sounded ideal - but I can't find them. I think they have stopped making them now. Looking around options, I spotted the <a href="http://www.teleskop-express.de/shop/product_info.php/info/p4541_TS-88mm-triplet-APO-Bino----90----2-eyepiece-pairs.html">TS 88 mm triplet</a>, that looks quite nice. They have 70 mm binos that look identical to the Helios Quantum 6 (and about the same price), but the 88 mm are not identical - although they look the same, the TS 88 are a couple of kg more than the Helios and have different supplied eyepieces (TS only have 2, but Helios has 3). BUT - the TS 88 mm is virtually the same price as the TS 70 mm. <b>If</b> it is the same quality, then it looks like something of a bargain (the Quantum 6 equivalent is around £250 more). My Manfrotto might struggle with 6.5 kg, but apart fron this is there a better choice? Regards, Stewart
  2. I know a bit about optics, mostly through my level 2 OU course in Physics. I'm comfortable with refraction. What I can't get my head round is the choice of diagonal size. Say, for example, that I bought an 80mm f11.25 refractor OTA with a focal length of 900mm. It will take a 2" diagonal but will also take a 1.25" one. I imagine that when looking at something relatively small (e.g. a planet) there will be no difference between the two, given that the image projected on the mirror will be very small. For wide field it might be a different story - but at f11.25 you're not talking wide field. Is there any advantage at all in going for a 2" diagonal (& eyepieces) on a scope like this? Stewart
  3. In reverse order: 3. Comet Halley. It went on for ages, but my favourite moment was watching it during a meteor shower. 2. Seeing Saturn's rings for the first time through my daughter's TAL reflector. 1. (Echoing Astro_Baby and Helen) naked eye views of the sky from rural Tanzania (about 150 miles away from the nearest electric light bulb). We do get dark skies up in North East Scotland, but it doesn't compare - I think the high altitude and an absence of industry played a big part.
  4. Gravity does indeed alter time. Maybe so, but you're rambling in the right direction. See What causes Gravity? and Why does Gravity slow Time?
  5. I've had a look at Purple Cloud's knowledgebase, which states that your index.html file should be saved in the httpdocs directory - check that that's where it is going. Check the file dates when you're looking at the ftp listings as well.
  6. Yes, it is. For a detailed explanation you could try this Wikipedia article on time dilation.
  7. It would be pretty difficult to completely sterilise a planet, at least if life on Earth is anything to go by. The Search for Extremophiles on Earth and Beyond, from Ad Astra magazine. Life has even been found 1.6 Km below the sea floor, at 100°C and under huge pressures (New Scientist article). I imagine that it would be easier to genetically modify ourselves to suit the conditions on a new planet instead.
  8. They are beautiful, and you can't mistake them for anything else when you see them. This is from 2006, near Blairgowrie: 45° might be a bit too far south, but I do know someone who claims to have seen them in Northern California. They're a modern phenomenon, the earliest description of them is possibly by Edward Maunder in 1882. (from Wikipedia)
  9. Up in your neck of the woods I'd expect a 500 item database to be woefully inadequate. At least I'd hope so, with the official opening of the new HAS observatory tomorrow. I take it it's still on? I'm planning on going along. I'm hugely impressed that the club managed to raise £75,000, and I'm looking forward to seeing what you did with it. Besides, I've never been to Culloden. If you're there it would be nice to meet you. I did try to buy a telescope from you last year, but I wasn't quick enough... I ended up buying one of AstroPhethean's cast offs instead (but I'm still very happy with it).
  10. Another option is the gravity tractor. Simply place a biggish spaceship close to the asteroid, and let it's gravitational attraction divert the asteroid onto a new course. Advantages: You can be very precise when calculating the effect, since all you need to know is the mass - you don't need to worry about composition, internal structure or rotation. You run less risk of simply breaking the target up into smaller (but still dangerous) fragments. Disadvantages: It needs lots of energy, since the spaceship will need to keep itself in position using offset thrusters. It also takes a lot of time (months to years, depending on the mass of the asteroid). Mirrors seem to be the favourite option, according to this New Scientist article.
  11. The equation is OK, but you've missed a few zeroes off the speed of light. It's 300,000 kps, not 300. Redoing the equation I get a value of 0.0000016%, which over 30 years comes to just over 1.5 seconds. (Assuming I haven't made any mistakes as well).
  12. If you are lucky enough to track down a copy, then I would heartily recommend "The Cartoon History of Time" by Kate Charlesworth and John Gribbin, starring "Junior Chicken" and "Alexis the Quantum Cat". It's the best (and certainly the funniest) introduction to time and space that I've read to date. Where particle sheep safely wave, Terry Pratchett's review of the book in New Scientist.
  13. I think you ought to leave visibility in. My back yard is pretty dark, Mag 5 on a good night, and 100 for Convenience - but I can only see the top 30 degrees of sky or so. That's very limiting. I agree with The Warthog that convenience has too high a weighting, though.
  14. I hope so - but the last analysis I found was this NOAA Press Release from April last year, when opinions were split between a below average cycle and an above one. Has anyone seen any more recent projections?
  15. There's a review of O'Meara's book here, by Brian Tung. He covers the equation as well: Up at the club site - Mag 6, seeing: 5, visibility 0.85, covenience 50, I'll go with the consensus of 0.05 for weather (it can't be much different from Aberdeen) - giving me 63.75.
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