Our Great Grandparent's Astronomy

Discussion in 'Other Skills' started by charlesmc2, Oct 8, 2018.

  1. charlesmc2

    charlesmc2 Scout

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    After derailing myself on the compass discussion, I thought it might be interesting to discuss some skills we are likely losing. I know I did not learn much basic astronomy in school. I always loved science and graduated with a BS degree in physics. I think I was too much into what made the stars hot, neutron stars, black holes and the like.

    For starters, how many times does the earth rotate on its axis each year? Hint: it's not approximately 365.25 days.

    I'm thinking in terms of identifying the planets visible to the naked eye. Watching for an opportunity to catch mercury just after sunset or before sunrise on those odd occasions it is visible. Or learning that venus has phases like the moon, but we never get to see a "full" venus. How about seeing how tiny a crescent moon you can catch just after a new moon. Or learning Orion, the Big Dipper, Polaris and Cassiopeia. Learning when noon is where you live. (Both our adult kids live in Lubbock, TX. There are a few days when their noon occurs after 2:00 pm, thanks to Daylight Saving Time and a location far west in the Central time zone. Another, why does the latest sunrise in the northern hemisphere occur about January 10, almost three weeks after the solstice.

    Incidentally, the answer to the rotation question is 366. The earth turns on its axis in about 23 hours, 56 minutes. The other four minutes are required to "catch up" to the sun since we are moving about it, just like you have to turn your head to catch up to something you are passing by in your car. Another way to see this is to consider that if the earth did not rotate at all we would still have one night and one day a year. We "lose" that one day every year.

    I've chosen some of the more puzzling things to consider, but most are simpler. My own grandmother, born in the 1880's and only educated through the 7th grade taught me a few. One I remember is to tell whether it would be wet weather or dry was to look at the phase of the moon. If the "cup" was relatively level, expect rain. The cup could hold water. (This happens in spring and fall, our wettest seasons where we live.) In summer when it is dry the "cup" is tilted over and is thus empty--no rain.

    What are some observations you think are worth passing along to following generations?
     
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  2. charlesmc2

    charlesmc2 Scout

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    Also, plant cucumbers early Easter Sunday morning. (And this from parents who observed a day's rest on Sunday.)

    OK, now how do they decide when Easter is?
     
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  3. NattyBo

    NattyBo Supporter Supporter

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    We in the northern hemisphere for the past couple millennia have been in a great era for celestial navigation using the pole star Polaris. Because of the earth's axis wobble this has not and will not always be the case. Around 4100 AD the pole star will have drifted to Gamma Cephei (Errai).

    https://stardate.org/radio/program/future-north-star
     
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  4. Beach Hiker

    Beach Hiker Traveller Supporter Bushcraft Friend

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    Easter is the first Sunday following the first full moon of the spring equinox.
    As a result its date can vary widely.
     
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  5. charlesmc2

    charlesmc2 Scout

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    The latest sunrise occurs almost three weeks after solstice because earth is closest to sun in winter (northern hemisphere) and thus moving fastest. It is easier to think in terms of when noon is. Solar noon occurs later and sunrise is a little later. Most of us live where the earliest sunset is in early December. Day length changes very little around either solstice and most rapidly around either equinox.

    A good source for this sort of stuff is www.sunrisesunset.com. You can look up data for your location. I'm goofy enough to like this stuff.
     
  6. Yknpdlr

    Yknpdlr Tracker

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    To find cardinal directions on earth using the moon, observe it before "first quarter" or after "3rd quarter" when cusps are visible ( the pointy looking lit top and bottom). Draw an imaginary line from top cusp to the bottom, extend it to the horizon, and that point will be very close to true south (in the northern hemisphere). It works even when the moon is visible in the daytime. Of course having a general knowledge of position of the moon in the sky and its track will tell you directions as well.
     
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  7. Yknpdlr

    Yknpdlr Tracker

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    Knowledge of the mathematics of orbital mechanics and geometry was so accurate in the 1600's that by measuring differences in observed time of eclipses of Jupiter's moon Io, one could calculate the speed of light due to differences in observed vs predicted eclipse event time as the distance from earth to Jupiter varies throughout the year. In 1676 Danish astronomer Roemer estimated that light would take about 22 minutes to travel a distance equal to the diameter of Earth's orbit around the Sun. This would give light a velocity of about 220,000 km/s, about 26% lower than the true value of 299,792 km/st.
     
    Last edited: Oct 10, 2018
  8. charlesmc2

    charlesmc2 Scout

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    I think we greatly underestimate the intelligence of people in ages past. Archimedes developed a way to calculate pi to great accuracy (although doing so by hand was extremely laborious.) He was on the leading edge of what would eventually be calculus. Tycho Brahe and Johannes Kepler established the orbits by observing the motions of the planets. Considering there was no fixed platform from which to observe that was pretty amazing.

    And then there was Newton. A man of first order both in physics and mathematics.

    Nature, and Nature's Laws lay hid in Night,
    God said, Let Newton be! and All was Light.

    Alexander Pope
     
    Last edited: Oct 11, 2018
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  9. ExAF1N1

    ExAF1N1 Purveyor of sharps and savory burnables. Supporter

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    @CowboyJesus , some of this may be of use for the navigation section of the course you'll be teaching.
     
  10. CowboyJesus

    CowboyJesus Supporter Supporter Bushcraft Friend Bushclass I

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    thanks for mentioning it-i have been watching and following!
     
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  11. Kacie

    Kacie Guide

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    My Grandpa said
    "When there's a ring around the moon,
    count the number of stars inside of the ring...
    expect rain in that same number of days."
     
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  12. Foulwind

    Foulwind Guide

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    What kind of drugs were they using back then to even think up the #$%^ they did then? I can spell algebra buts that's about as far I go with it!
     
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  13. charlesmc2

    charlesmc2 Scout

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    Newton, Beethoven, Bach and a handful of others were not human. But seriously, they were capable of thought and concentration we cannot imagine. I wonder if there will be another like them. Too many distractions. We can progress by group work and collaboration, but the fundamental advances are different.

    I love the statements like "our knowledge is doubling every 10 (now 5) years." I'm sorry, but sheer volume does not equate to quality any more than someones's dissertation equates to Newton's Principia. Einstein just might have been the last. Only time will tell.
     
  14. Kenneth

    Kenneth Supporter Supporter

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    I was told by my dad that when I see a pecan tree start to bud the danger of frost is over. Sure enough over the years I watched the neighbors pecan tree in the his front yard and year after year it was true.

    I saw the north star last week on October 13th in Alaska, we went on a northern lights viewing and the guide showed me the big dipper and leading to the north star.

    The funny thing that I was told, the better you see the Aurora Borealis with your eye, the worse the pictures will be, however the better the pictures turn out the worse it is see what your eye. They got a good picture of me with their professional camera and I did see part of the lights dance for about a minute.
    DSC01630-1.jpg

    GOD Bless you and your families

    Kenneth
     
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  15. charlesmc2

    charlesmc2 Scout

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    I don't remember the exact year, but it was the late 90's. I was visiting my sister out in West Texas near Midland. My wife called me, it was late, sort of frightened me because we just don't call late. One of my friends at work had called the house to tell me to go outside. The aurora was putting on quite a show. I knew the northern lights were visible in Texas at times. My mother had watched them one early morning some 40 years previously. (Why she didn't wake me to see it I never knew.)

    Incidentally, rural West Texas is one of the very best spots for night time star viewing. Those of you familiar with that part of the world know the air is clear and dry. And none of those pesky trees to spoil the horizon.
     

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