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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunars and pixels
From: John Huth
Date: 2010 Dec 13, 09:33 -0500
From: John Huth
Date: 2010 Dec 13, 09:33 -0500
Jeremy -
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Keeping up with the grind
The class is titled "Primitive Navigation" - it's something of an excuse to teach some physics, climatology, statistics and the like under the rubric of navigation. There's another course at Harvard called Celestial Navigation that has a long and distinguished history, but doesn't have enough science in it to justify it counting toward credit in the sciences. This was designed explicitly to satisfy a science requirement. Mainly majors in humanities take it, so I cannot assume too much mathematical sophistication.
Some slices of the course:
Physics:
vectors, displacement, velocity, acceleration
forces, torques
pressure
fluid statics
fluid dynamics
Newtonian gravity
Electromagnetic waves, polarization
Water (surface) waves
Refraction
Diffraction, interference
Some thermo - adiabatic cooling, heat transfer, convection, equation of state
Earth sciences, climatology etc
Ekman transport
Ekman spirals
Ocean currents
El Nino
Global convection cells
Jet stream
Monsoon
Fronts
Cyclonic storms
Ionosphere
Tides
Misc.
Birds
Bioluminescence
How the brain stores spatial information
Navigational cultures
Polynesian
Norse
Arab
Western european
Boat stability, design, hull speed
Sail design
Statistics
Mean, std. dev
Uncertainties
Propagation of uncertainties
Variance, co-variance
Correlations
T-test
All of this is mixed together with applications to navigation. Example - we do one assignment on radio triangulation, where we give them cheap AM radios and they use the latitude and longitude of transmitters to find their latitude and longitude by finding the bearing of nulls on the radios.
I also had the opportunity to correct many of the misconceptions in popular literature. For example - in the static theory of tides, one often hears something like "the pull of the moon creates the near side bulge and the centrifugal force creates the far side bulge" I see this so often, it gets me irritated - so I walk them through a proper discussion of tides.
There's a similar problem with the description of lift in popular texts, where Bernoulli is invoked, but there's no mention of the role of fluid inertia or viscosity, which are absolutely essential to a proper theory of lift.
Then, there are the final projects as you saw.
Best,
John H.
On Mon, Dec 13, 2010 at 7:34 AM, <Anabasis75@aol.com> wrote:
What class is this and what level of education are these students? Just curious.JeremyIn a message dated 12/12/2010 1:55:52 A.M. Central Asia Standard Tim, apacherunner@gmail.com writes:
Since this was discussed extensively just a little while ago, I thought I'd share the experience of some of my students in doing lunars with pixels. Some of the trials and tribulations may sound familiar to some of you.They calibrated their pixel width using stars in Leo, and then did a Sunset - Lunar time difference and did shots of the Moon and Regulus. One of the bigger issues was pixel bleeding - in order to get a decent image of Regulus, the disk of the Moon became overexposed and quite fuzzy. They only did as well as 5 degrees in longitude using this, and their conclusion was that navigators "back in the day" had to have considerable patience to do lunars.Here are some of the other projects they didclepsydraorientation of saxon and norman churchesviking sun stonemap-making using the techniques of Lewis and ClarkLatitude and longitude from sunset/sunrise and meridian passageAccuracy of backstavesNocturnalsConstruction of a sun compassLatitude and longitude from satellite dishesAll of them had to do some statistical analysis of their results. I was pleasantly surprised by some of the results. In particular, I was amazed at the accuracy of the sunstone. They used some optical quality calcite, and used it to find north at sunset. They were systematically off in their measurements, and were perplexed until I pointed out that the sun was (is) setting south of due west this time of year. When they put this in, the measurements were spot -on. As we talked about before, one doesn't know if sunstones were really employed by the vikings. I'm simply pointing out that they do work, and I was surprised at how well they did.
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Keeping up with the grind
