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Thread: Astronomy

  1. #1
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    Astronomy

    I became interested in astronomy in the late 1960s from Thomas S. Kuhn The Structure of Scientific Revolutions. This is a theory of scientific revolutions, but it also draws on examples of such revolutions, including the Copernican Revolution. Around the same time The Jodrell Bank Observatory was in the news, especially the Lovell Telescope, using Radio astronomy. Another event that caught most people's imagination was the first human landing on the moon in 1969, Apollo 11.

    Then I left the subject and didn't return to it for many years. Now at last humankind is beginning to explore the solar system with probes being sent to most of the planets. The earliest was Voyager 1 in 1977 which is still operative and recently left the sun's gravitational pull (terminal shock), though this is still debated, and is on its way through outer space, bearing a Golden Record in case an alien civilisation finds and can read it. There is, of course, a lot more, including Voyager 2. These also began to map and image the nearer planets their moons and other objects like asteroids and comets, a job that is still incomplete and that the probe New Horizons will soon be doing to do a preliminary mapping of the dwarf planet Pluto. The other major event is the Rosetta Mission to land on a comet and investigate it.

    This is a very exciting time in astronomy, with much happening and much to discuss.

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    Most of what I've learned about astronomy was prompted by threads on Lit Net over the past four years that I've been here. It is not that I didn't hear about astronomy topics. I wasn't interested.

    For example, until recently, I didn't realize that the Big Bang was the beginning of time and space. I mean, I was shocked, but now I don't see how it could be otherwise.

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    I didn't realise there were other threads on astronomy. I did a search and came up with nothing. There are well over 600 threads on serious discussions alone, yet I got no hits. Perhaps I am doing something wrong in my searches...

    Anyway, space travel owes a lot to the work of someone I never heard of before - Michael Minovitch and the concept of gravity assist. See this website for details: http://gravityassist.com. Briefly until then rockets were shot up without using the slingshot technique of building up speed by this method, often several times, for example by circling the moon en route to develop enough slingshot speed to reach the goal.

    Big Bang is still a theory. I can't even see how it can be proved, but one never knows…

    Enormous strides in recent years, and have mapped all the inner planets and their moons with robot probes that do the job without risking human lives by sending people up into space.

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    There aren't specific threads, but comments posted that got me thinking and reading stuff on the internet and the local library.

    I enjoyed the Minovitch article. He overcame the need for most of the propulsive energy originating from earth to get to the other planets. There is also the radiation issue that has to be taken account of when we leave the magnetosphere of earth. I don't know to what extent that has been solved.

    Everything's a theory, but I don't see any reason to doubt the big bang.

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    I don't think the radiation danger of humans in space has been addressed. It may be this that will prevent sending humans to Mars.

    Yes, it is the abstract nature of understanding the galaxies, Oort cloud, and much else that puts me off trying to grasp even bigger issues like the big bang theory. Right now we have barely begun proper exploration of the solar system in which we live, let alone our home galaxy the Milky Way. The problem with much exploration of space is the abstract nature of the subject.

    Yes we have more and more powerful telescopes and even ones in space, like Hubble and what we learn from that is the many exoplanets there going round other suns (stars), and even double stars, with planets that hop between them. There are even rogue planets that have been expelled from their orbits by some violent space event, still less of their exomoons. The rate of new knowledge accumulation is very rapid.

    Basically, we have not progressed beyond the initial exploration of the solar system we live in. even that is only just at the start. We are about to learn something of the farthest planet we know of, Pluto, if all go well. There are many moons around our neighbouring planets that are quite weird and we still know little about. Perhaps soon probes will be sent to one of these to survey them.

    Some space websites:
    EarthSky is a good one that is updated daily. There are many others, see this list.

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    I agree there is a lot to know about our own solar system. I thought we would have known by now from information from the Curiosity rover whether Mars once had life or not, but that is still unknown. There are other places in the solar system to look for life.

    Whether one is discussing astronomy or quantum physics one has to separate the facts from the theories which for an outsider (and perhaps even an insider) is not easy to do. The facts are what are going to be there whether the current theories survive or not. For example, one will have the quantum enigmas (based on double-slit-type experiments) to explain whatever quantum theory or interpretation becomes dominant. Similarly, one will have the cosmic background radiation to explain whatever one comes up with for a theory replacing the big bang.

    One of the theoretical consequences (not direct facts of the cosmic background radiation) that is derived from the big bang has to do with the actual age of the universe. This is likely based on theoretical assumptions that astronomical constants are actually constant, like the mathematical constant pi, throughout space and time. It probably also assumes that conservation-symmetry laws are valid throughout space and time. If they aren't, how confident would we be in a value like 13.7 billion years for the age of the universe?

    Another place where theory can get messed up is through a metaphorical way of looking at the universe. Is the universe more like a deterministic machine or an organism? Was it created or born?

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    You are right, of course, and you share an interest in the search for life with many others. SETI, the Search for Extra-terrestrial Intelligence is one of the reasons many want to explore outer space.

    My reasons are more mundane and to do with discovering our own solar system. We have barely begun that task, and the Voyager series contain the Golden Record, in the hope of contacting interstellar intelligence.

    I have been trying to bring together a very brief overview in this post of the little we do know, and have learned a lot from the Astronomy Now Special Edition on The Planets.

    Pluto, discovered only in 1930, is the furthest planet (dwarf planet) from us though there may be others further out. The smaller neighbours of Earth are all rock planets, while the middle ones from Jupiter to Neptune are gas giants with many moons of their own. Jupiter has 64 moons and one of these has its own moon. We have only recently been able to take a closer look at this gas giant since Cassini flew past it. Its main purpose was to study Saturn with its rings and its 62 moons. Cassini was launched in 2000.

    There are many exciting probes still to do just to map what we know of our sister planets of the solar system and their almost innumerable moons of ever size, shape and peculiarity.

    The last part of your post is itself interesting Another place where theory can get messed up is through a metaphorical way of looking at the universe. Is the universe more like a deterministic machine or an organism? Was it created or born?. I agree this is how to get tied up in metaphysical knots, and would not know how even to begin addressing that.

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    I've heard that less is known about our oceans or the life in them than is known about the solar system, but that might be an urban legend.

    What do you recommend reading about the solar system?

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    The speed of development is so fast just now that I suspect any book on the solar system would be quickly out of date. I'd go for a subscription to a popular astronomy journal, as you are in the USA Astronomy is probably the best. But it is not just about the solar system, like all journals it covers all aspects of space. This website on best popular astronomy books might be a good place to start.

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    I got back from a walk to the library and where I picked up David A. Rothery's "Planets A Very Short Introduction". It was written in 2010, but I am only looking for keywords and other vocabulary.

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    I find that much of the advanced astronomy journals are too much into "imaging", as well as the galaxies (I am satisfied with just the solar system and what we can see from in the sky from our homes) and needing advanced telescope and camera equipment. I would love to get more into astronomy but as I am old and infirm it is too difficult to do so (old dogs and new tricks…). In Europe we have more junior journals like Popular Astronomy, both in English and in Swedish. Perhaps you have an American equivalent...

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    There are a lot of sources. I thought you might have one you were interested in reading. I do have binoculars and I've looked at the moon and Venus with them, but basically I don't know what I'm looking at. I think I have spotted Mars and Jupiter, but who knows?

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    I'm not sure what you mean by sources? Can you explain?

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    Mini-Observatories

    A pair of binoculars is what I have, too, 7x50, actually quite good quality, but holding binoculars for any length of time is tiring and quickly starts to wobble. Even a small bottom-end telescope on a tripod is better. But these days observatories are often built in the garden, some are rather basic, like the ones on this website. Others are small observatories, more usual owned by a local astronomy club. I don't have one near me, as we live in a fairly low-population part of Northern Sweden. Nor am I good at making things like that. I'm also in my early 70s so I don't feel able to spend a lot on an interest I acquired late in life.

    Many specialise in a planet like Jupiter, or Earth's moon, even the sun, though I would not recommend that as you have to be very careful not to accidentally risk blindness.

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    The sources are books or internet articles, basically something to focus our attention on and get the vocabulary.

    The link you referred to made me think that maybe I could build my own telescope. I did want to do that as a child, but felt I had to grind the mirror as well. I'll see if I can find Richard Berry's book on making a telescope. The binoculars I have is a 7x50 Nikon Stayfocus Plus II. I don't know it it is any good or not as these things go. I don't look at the Sun through them, but I have seen a solar eclipse through the leaves of a tree. It was amazing. Many eclipsing suns on the ground.

    One of the other things I wanted to build was a board to experiment with double slit experiments.

    Being in a low population area would mean you can see more stars. I live in a large community outside Chicago, but when I get to Wisconsin and look at the night sky the world is very dark. The night sky stands out.

    I think I might try Dave Trott's plan to build a telescope found in one of your links: http://davetrott.com/telescope-proje...ect-telescope/
    Last edited by YesNo; 11-12-2014 at 01:27 PM.

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