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GeeKay

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Everything posted by GeeKay

  1. Ah, yes, I understand now. Thank you, Acme. One thing that hadn't been clear to me until reading this NASA article was the propensity solar flares have for charging up and accelerating particles that lie in their path. I think it was this more than anything else that created the confusion in the first place. On a related issue: I heard that aurora had recently been detected on Mars. I don't know how extensive this was, but given that Mars doesn't have a global magnetic field, I'm a bit puzzled how solar activity, such as CMEs, are able to generate aurora on Mars in the first place. Many thanks.
  2. I am trying to understand the composition of solar flares: whether they are purely electromagnetic, for example, which to say they ALL propagate through space at the speed of light, or else composed of (or include) high-energy particles. The reason for the 'ALL' is because I keep coming across conflicting descriptions of solar flares, with many accounts actually referring to CMEs, or else discussing solar flares and CMEs as if they were merely two terms for the same phenomena. For example, did Richard Carrington (and most of the world) witness in 1859 a solar flare or a CME? I've come across both explanations. Finally, it seems that solar flares cause aurorae, and at the same time they most definitely do not cause aurorae. . . Help!
  3. So I take it then that even if the primary body was a white dwarf, or something even denser - a neutron star, say - the same Roche limit rules apply, as they pertain to a far less dense satellite in orbit round the above object. . . a water-ice comet, to take an extreme example? I mention this because some commentators on the internet, in discussing the Roche limit, referred to relative densities. Unfortunately, for whatever reason, it all left me feeling confused, rather than enlightened.
  4. Thank you. That's what I wanted to hear
  5. One possible one-way voyage to Mars (or anywhere else for that matter) involving human visitants could be achieved by those suffering from terminal illnesses of one kind or another. Obviously, it would be essential for the astronaut not to be incapacitated by the illness - at least remaining reasonably fit and well until the end of the mission. Computer technology would enable a dignified, and possibly private, act of self-administered euthanasia. Many observers, I'm sure, would still regard such an enterprise as ghoulish. Still, if I were granted a "once in a lifetime" opportunity to go to Mars under these terms, would I accept it? Oh, yes, for sure
  6. If I may quote Wikipedia here: "The Roche limit is the distance within which a celestial body, held together only by its own gravity, will disintegrate due to a second celestial body's tidal forces exceeding the first body's gravitational self-attraction." This being so, in the case of a Solar-mass body, does its Roche limit, as it applies to a given satellite, remain the same, regardless of its diameter? In other words, would the limit stay put, even if the Sun were magically shrunken into a white dwarf, while retaining its original mass? Many thanks.
  7. While it seems that some scientists/astronomers/pundits now have a fair idea about the average distribution of dust grains in outer space (one per million cubic metres, according to one source, ref. link below), I can find no such confident claims when it comes to the distribution of micrometeoroids in the interstellar medium - i.e. objects around 300 - 500 micrometers diameter (or wide). The silence here - if silence it is - intrigues me almost as much as my desire to know the answer. Maybe the answer lies in the future. Who knows? I don't, that's for sure http://science.jrank.org/pages/3656/Interstellar-Matter.html
  8. Yes, my apologies about the "shouty" font. I must have hit the wrong button. Re solar power issues, I do wonder if Earth-based systems will always be sufficient, given our soaring energy needs. The last time I looked we were, globally speaking, consuming around 500 exajoules per annum, and while there will always be dips due to recessions etc, the trend, for all its sawtooth profile, remains remorselessly upwards. So much so it seems that unless there is a global catastrophe of some kind, or else a radical shift in thinking, it will continue to soar. I accept that new technological advances in the nearer term - both with regards to solar energy gathering and the perennial problem of energy storage - may satisfy our needs for quite a while longer yet, and so keep the industry down here on Earth. And, yes, I share the concerns about microwaves beaming down from space. I suppose we will first need to become a true spacefaring species before we learn to harvest all the energies that requires from the environment of space itself. I don't know if this is putting the cart before the horse, or whether the horse is having a free ride, but I'll let posterity decide about that. Many thanks for the links and helpful responses. The Elon Musk link is a gem.
  9. 'Hyperspace' by Michio Kaku is very good on the subject of parallel worlds. Highly recommended - and not just by me!
  10. Assuming for the moment that the technology will be available in the not-too-distant future, could the Earth's energy needs be met entirely by solar power one day? By this I mean having the Sun's energies directed from space down to us on Earth via microwave beams, say. As a follow-on question, are there any practical limits to how much energy could be harvested from the Sun? I have in mind an array of gigantic solar panels orbiting the Sun at fairly close quarters - the ever-present threat of solar flares and CMEs notwithstanding. But there may be other solutions about which I am entirely ignorant. Finally, is the physics concerning the above already in place, if not the technology and political wherewithal? Many thanks.
  11. My apologies. By a "non-magnetically charged object" I meant non-ferrous minerals and metals, like copper, nickel, cobalt, etc.
  12. Thank you. To clarify things then: any non-magnetically charged object gravitationally drawn to an ultra-compact body like a neutron star can, depending on its trajectory, impact upon any part of its surface, not just at its magnetic poles.
  13. Neutron stars have been described as the most powerful bar magnets in the known universe. This being so, is it possible for the magnetic fields of such compact objects to take precedence even over their gravity fields? An example: would a small object captured by a given neutron star wind up impacting upon one or other of its magnetic poles, rather than gravity pulling it down to impact anywhere else on the star's surface/photosphere? Many thanks.
  14. Many thanks for the explanations - brick analogies and all Yes, I think I finally understand the equation now. On a personal note, I suffered badly on the maths front at school. Partly the fault was my own; but I do contend that a substantial chunk of it was due to the teaching practices typical during those times, especially when it came to rote-learning techniques. This method has its uses, but for me back then, especially when it came to the teaching of maths, it was heavy on the 'how' and light on the 'why'. It wasn't until I did GCSE Maths as a mature student that I began to understand that maths is a language - and a wonderful language at that. At least I know that now, even if I remain a poor reader of numbers. I just wanted to say that. End of personal note.
  15. Regarding these "two pieces of information, force and time", I'd appreciate it very much if you could provide me with an example how a given final velocity may be calculated. Many thanks.
  16. The quote below is the most succinct description I've found on the net explaining the relationship between spacecraft velocity and performance: "The speed of a rocket is directly affected by 2 factors. The first is mass ratio, which is a ratio the weight of the rocket at lift-off compared to the weight of the rocket at engine shutdown. The second factor is specific impulse, which is the amount of thrust produced from each pound of propellant per second. The higher the mass ratio and the higher the specific impulse, the faster the rocket can go." Mass ratio I understand. Likewise, I can get my head around specific impulse - although I still have to strain it a bit. What I don't understand is how all this translates into spacecraft velocity. It's all very well to talk about exhaust velocity, but at risk of sounding fatuous, were I a petrolhead wanting to buy a sports car, I might be interested in fuel consumption (possibly) and knowing how efficiently the exhaust functions (well, maybe) but really, I'd love to know how fast the car goes. Unfortunately, concerning specific impulse and 'forward' velocity as it apples to spacecraft, I can find nothing anywhere that can join up these two dots. Many thanks. PS. Again, I apologise for the crassness of the question. But how can one find out if you don't ask?
  17. I've just read an article on the BBC website (see link below) in which experimentalists have reduced the speed of light by remodelling photons. Does this mean that the frequency of light is also reduced? http://www.bbc.co.uk/news/uk-scotland-glasgow-west-30944584
  18. Yes, on reflection I have to agree. . . at least in part. There were some fine moments in the film, especially visually. But it did drag in places. I'm afraid I still don't understand the 'timeloop' sequence, though the tensions it created certainly added to the drama. Timeloops? Is this a reading of the multiverse concept?
  19. Yes, I should have done my homework about quasars before popping the question. Three additional thoughts, though: (1) possible disruptive effects caused by the 'merging' of two SMBHs - gravity waves etc? (2) colliding galactic gas and dust clouds? (3) dark matter? I mention these colliding aspects, having ascertained that the closing velocity between the two galaxies is approx 110 km/s (or very roughly equal to the distance between the Earth and the Moon covered in an hour). This doesn't strike me as inordinately fast, at least not by cosmic standards. But it's still fairly brisk - brisk enough, I would imagine, to have all manner of effects at the 'local' level - the interstellar medium, planetary systems etc.
  20. With regards to the future merging of the Andromeda Galaxy with our own Milky Way, would this event create a quasar? If so, would this in turn eradicate all existing life in both galaxies? (assuming, of course, that Earth isn't the only repository of life in our part of the universe). Many thanks.
  21. I'm no expert on this, but I'm inclined to agree with Moontanman about seemingly being able to fly around on Titan, using a pair of borrowed wings. I wonder if I read it in Starship Century - an article by Robert Zubrin, possibly?
  22. With regards to Interstellar (which as enjoyable as it was, induced in this viewer some time-dilation issues of its own, given its length) I found this interview in a recent Scientific American article, in which Kip Thorne explores some of the physics contained in the film. PS. I'm not sure if this link functions properly, but it's worth a try. http://blogs.scientificamerican.com/observations/2014/11/28/parsing-the-science-of-interstellar-with-physicist-kip-thorne/
  23. Many thanks: l learnt a great deal about optics from this thread. So the upshot then is that the size of the pupil determines its capability to resolve incoming light within a given spectrum of wavelengths. And this limiting factor applies whether one is viewing an object with or without the aid of magnifying glasses, and so forth. So the only way a human being is able to 'view' infrared radiation, for instance, is to use an infrared scanner of some kind, an external device that detects infrared radiation - i.e heat - and converts this radiation into 'visible' light. Re depth of field: I well recall a childhood memory of my brother and I taking turns to watch incoming traffic through a pair of fairly powerful binoculars while travelling in our father's car. It made for quite a strange visual experience - comic-strip Special Relativity for beginnners almost. Not to be recommended while driving, however.
  24. Yes, I'm looking forward to the advent of the James Webb Telescope and although I'm not superstitious, I'll be tempted to cross my fingers when launch day finally comes. Enthalpy, thank you for your comments about the transparency of the atmosphere. Intriguingly, the Bortle Scale - or someone referring to it - did claim an upper naked-eye limit of +7 magnitude, albeit under 'exceptionable' viewing circumstances. If so, then I guess this degree of clarity would also apply to space itself.
  25. If glasses do not increase the resolving power of the eye, what's the situation with binoculars, telescopes etc? Or is there a trade-off here between resolution and field-width? I'm sorry if this seems a stupid question.
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