Search results for query: *

  1. tfr000

    C/C++ Real Programmers don't use C++

    More compute power is good. The stuff I can do on my PC today in minutes would have bogged down the time-share minicomputers of yesterday for hours, to the point where the other users would have complained. I am, however, somewhat in agreement that we've mainly prettied up the interface. For...
  2. tfr000

    A What is the cause of lunar nodal and apsidal precession?

    Well if you're comfortable with some math, has a (brief) chapter on the Moon's motion. They didn't include the CDs back when I bought my copy. Danby can be a little terse - by which I mean, I sometimes feel like I would have liked a little more explanation...
  3. tfr000

    A What is the cause of lunar nodal and apsidal precession?

    No, he doesn't, but some other authors do. I don't think their simplified derivations would give you any kind of reasonable approximation of reality. The definitive semi-analytical work on lunar theory is: Good luck with it. He worked on it all of...
  4. tfr000

    A What is the cause of lunar nodal and apsidal precession?

    Well... that didn't quite format right, but you get the idea. The first number is for lunar perigee, the second for lunar ascending node.
  5. tfr000

    A What is the cause of lunar nodal and apsidal precession?

    Mean annual motion of the: perigee node caused by: Principal solar action +146426.92 -69672.04 Figure of the Earth +6.41 -6.00 Direct planetary action +2.69 -1.42 from Roy...
  6. tfr000

    C/C++ Real Programmers don't use C++

    Ha... I actually used to use TECO and had to key in the bootstrap with the front panel switches a couple of times... we used to write character-cell computer games for the VT52's. Slightly more complicated than Pong, but only slightly.
  7. tfr000

    The Force Awakens Spoiler Thread

    Yup. They used to play the Star Spangled Banner, or something, over a waving flag. Or was that when they came back on in the morning? ... it was a long time ago...
  8. tfr000

    The Force Awakens Spoiler Thread

    Well, I've seen it. I liked the older, wiser, mellower, more care-worn Han and Leia. That meshed with the old series very well. The bigger, better "death star" was interesting just for its vastness, but it's the 3rd one now. "Anakin" number two... I suppose it does play well that these young...
  9. tfr000

    A On a Clear Day, at 6 ft tall, at the waters edge ....

    Not unlike the oft-asked question, "How far can you see with your telescope?" "Well, I've seen 3C273..."
  10. tfr000

    What's so great about A Space Odyssey ?

    Vastly superior alien life shepherding the development of the human race.
  11. tfr000

    Today I learned

    Today I learned that the Higgins Armory Museum closed a couple of years ago! Probably the coolest museum I have ever had the pleasure of wandering through...
  12. tfr000

    Trying to calculate Orbit figures with C# and 3D space

    Several books here would probably help you. None of it is terribly difficult to understand, but it takes a while to get your head into that mode of thinking.
  13. tfr000

    Quick question on orbital eccentricity and mechanical energy

    I'd say the answer to your question is "yes", but I think you're looking for more than that. Maybe you should elaborate.
  14. tfr000

    Can you solve this riddle?

    Or maybe with "Ladle rat rotten hut".
  15. tfr000

    How to make a wanted shape from a raw material?

    Yup. The skill is called "flat filing". About 100 years ago, one was required to have the skill to make machine parts by hand if no other means were available. One of the steps, for iron parts, was to first anneal the metal, that is, to heat treat it until it softened up some, to make it easier...
  16. tfr000

    What's so great about A Space Odyssey ?

    Reviving an old thread... 2001 the book was awesome. The Discovery's final destination is Saturn, not Jupiter, in particular the moon Iapetus. Seems Iapetus is bi-color - very bright on one side, very dark on the other. This is true - Iapetus does indeed have a large, bright spot on it. In the...
  17. tfr000

    Solar System dynamics

    You have to figure the positions of all the planets in their orbits. The Sun is on the opposite side of the center of mass for each. Then you add them all up. Not terribly difficult, but non-trivial. That's the numerical way to do it. Analytically, I don't know. You could assume circular orbits...
  18. tfr000

    Are you afraid of the stars?

    None given. He discusses fear in general, fear of the dark in particular, and how it affects astronomy - we (humans) want to light up the dark. After the above statement, he does go on to say that he sympathizes, "The stars are utterly alien, completely and forever beyond our control." I've...
  19. tfr000

    Are you afraid of the stars?

    "At a deeper level, I've had several people tell me that the stars scare them." -Tony Flanders, Sky & Telescope, Jan. 2016 issue
  20. tfr000

    My favored scientist quotes

    The scientist does not study nature because it is useful to do so. He studies it because he takes pleasure in it, and he takes pleasure in it because it is beautiful. If nature were not beautiful it would not be worth knowing, and life would not be worth living. I am not speaking, of course, of...
  21. tfr000

    Why a 6dB attenuator for receiver effective sensitivity test

    6 dB, as far as I know, is just a sort of standard value used for attenuators and hybrid combiners. It's enough to squash any reactive-ness in the load. Like some of the above posts said, you don't want your equipment feeding into reactive loads - you will generate all kinds of distortion, and...
  22. tfr000

    Detect Window/Door opening closing using sensors

    Simple IR motion detectors are the way to go. Wiring up all your doors and windows is a pain.
  23. tfr000

    Gravitational pull of Earth and escape velocity

    "Hyperbolic excess velocity" is what you're looking for here.
  24. tfr000

    Stargazing Some tips for a better experience of stargazing using 76 mm telescope

    You'll also need some kind of app to tell you which constellations are above your horizon tonight. In the old days, we used a planisphere... I still have one.
  25. tfr000

    "WT1190F" is the name for space junk that will hit Earth

    Sort of like J002E3...
  26. tfr000

    Cool ways to use the Pythagorean Theorem

    I used it (iteratively) to generate π once.
  27. tfr000

    Stargazing Some tips for a better experience of stargazing using 76 mm telescope

    Do you know the constellations? If not, learn them. Once that's done, it becomes much easier to decide what to look at. You will need star charts. Wikipedia's aren't bad:
  28. tfr000

    How to know cos sin tan

    We learned "Oscar Had A Heap Of Apples". But then you have to remember that the order is sin, cos, tan.
  29. tfr000

    Measurement of a missile's trajectory and maneuver

    How realistic do you want to get? Solid rocket motors can have different thrust profiles by varying the shape of the burning surface of the fuel. What about air drag? Acceleration ("Gs") depends on those and also on whatever maneuvering is done. Guidance is complicated, especially if you're...
  30. tfr000

    Especially unreasonable requirements to get your degree

    Yup. Back in pre-computer days, offices full of "computers" (i.e. human beings who punched adding-machine-type calculators) did the work. I have some older books (1930s-1940s) which show one how to organize the calculations for celestial mechanics with that method.
  31. tfr000

    Kepler's 2nd across a system of planets

    Yup, makes perfect sense.
  32. tfr000

    Kepler's 2nd across a system of planets

    An interesting question, which I have just seen for the first time... Does Kepler's 2nd mean that, for instance, both Pluto and Mercury sweep out an equal area over 1 hour? My gut reaction, without calculating anything, is "yes".
  33. tfr000

    Color code of resistance

    Also allows design of one board which can be "programmed" via jumpers to do a number of different things. Often used to disable/enable certain premium features.
  34. tfr000

    Rent an Apartment, Buy House, Buy Mobile Home or a Trailer?

    Buy. Think of it as an investment. It doesn't have to be anything big and grandiose.
  35. tfr000

    Color code of resistance

    Yup, very common in industry practice. One incorporates a number of "jumpers" into the circuit design. Removing or adding zero-ohm resistors at those points selects certain circuit behavior - for instance, choice of 5V or 3.3V power.
  36. tfr000

    Orbital velocity

    Well, yes. Newton says the force between them (the Earth and whatever) is proportional to the product of their masses. Therefore, the Moon orbits a little faster, in the same orbit than say, a baseball. A basketball's orbit would not be noticeably different from the baseball's. What are you saying?
  37. tfr000

    Cyclists are a pain in the rear

    I once was behind a large truck. The trucker, I gather, did not like cyclists. Upon coming alongside one, he lugged the engine, or something, and blew out an enormous cloud of black soot all over him. I used to try to stay out of traffic when I rode.
  38. tfr000

    Orbital velocity

    Well, if the satellite's mass is large enough, it's not (independent of mass). For instance, the Moon. However, if the satellite's mass is something like 1 ten-billionth of the mass of the body it's orbiting, and another satellite's mass is 5 ten-billionths, then you will see negligible...
  39. tfr000

    What can glue condom material to hard plastic?

    Gorilla glue (polyurethane glue) expands quite a bit as it cures - it foams up. So there is that to consider.
  40. tfr000

    Computing osculating orbital elements

    BTW, if you want to get deep into such things, may I recommend this author?
  41. tfr000

    Computing osculating orbital elements

    Depends on what you want out of it. If you start with heliocentric, J2000 pos/vel, you will get heliocentric, J2000 orbital elements. Just be careful in doing your comparisons with someone else's results (even NASA's) - if they started with, for instance, barycentric, J2000 pos/vel, their...
  42. tfr000

    PCB Design program of your choice

    No, but it is annoying to have to learn "the Altium way" to do anything at all, even something relatively uncomplicated. Unlike, for instance, LTSpice, which you can use virtually immediately just by poking around a little. The board I wanted to design (with Altium) was very basic. I had to pore...
  43. tfr000

    Is radiation pressure a thing?

    Ya know, I've never thought about it before... light for propulsion is always presented as an outside source fired at the craft.
  44. tfr000

    PCB Design program of your choice

    I used Altium for one board design. Not at all intuitive. It took a couple of weeks to get where I could use it effectively.
  45. tfr000

    Is radiation pressure a thing?

    Yes. One has to account for solar radiation pressure for exact calculations of (Earth) satellite orbits. Google "solar sail".
  46. tfr000

    Today I learned

    Pfft. Remember back in the 70's, when all of the studies said we should eat chemically hydrogenated oils instead of animal fats, because they were better for us?
  47. tfr000

    Destruction of Solar System by passing Star

    Not immediately anyway. But then 10,000 or 100,000 years later, Jupiter, in its new orbit, has pumped up (or down) all of the inner planet's orbits hundreds of times. What about the asteroid belt - a new late,late heavy bombardment? Probably millions of years before it all settles down again...
  48. tfr000

    Insights Think You Know Pluto? - Comments

    11 of 13. Guessed a few of them.
  49. tfr000

    Long Distance Laser Beams

    Only if the target is near the plane of Earth's orbit... i.e. at the Ecliptic poles, this doesn't happen.