Just a passing thought for those who must teach differential geometry, either as part of a math class or a relativity class, or just as an interesting feature of coordinate systems, which almost all physics classes use.
This is a real-world example of what is known as a "coordinate patch". The collection of all coordinate patches that cover a manifold (space) is known as an "atlas". And we see that if one is using lat-longs you are forced to use more than one coordinate patch to cover the surface of a two sphere (or in our case a slightly deformed two sphere.)
Joel Rauber
| -----Original Message-----
| From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
| bounces@carnot.physics.buffalo.edu] On Behalf Of Michael Edmiston
| Sent: Thursday, February 16, 2012 2:10 AM
| To: 'Forum for Physics Educators'
| Subject: Re: [Phys-l] polar grid navigation
|
| Well... you might try finding something about it from people who have
| actually been in Antarctica and have used grid-north maps.
|
| Below are some things I found.
|
| * * * From
| http://passporttoknowledge.com/lfa/QA/computers/Directions,Time,ZIP *
| * *
|
| QUESTION: How do you give directions at the South Pole? Wouldn't
| everything point north?
|
| ANSWER from Craig Mundell
| You are correct. Theoretically, every direction from the South Pole is
| north. To get around this problem, people in the U.S. look at the
| continent as a grid map with McMurdo Sound to the bottom of the
| page and the Antarctic Peninsula to the upper left of the page. They
| then use directions like it was any other map, i.e., the top of the
| page is
| north, bottom south, etc. In fact, with the grid map system the navy
| pilots use here, they actually fly north from McMurdo to get to the
| South Pole.
|
| ANSWER from Bob Loewenstein on February 8, 1995
| Geographically speaking, every direction at the south pole is North
| (except up and down). But we do have to tell people things, like the
| wind direction is so and so. To do this, we adopt what is called a
| 'grid
| north' system, where north is in the direction of zero longitude
| (toward
| Greenwich, England). East is 90 degrees, South 180, and West 270.
|
| * * * Who are Craig Mundell and Bob Loewenstein ? * * *
|
| By doing some Googling it appears that Craig Mundell wrote this while
| he was
| living at McMurdo Station and working in aviation support for getting
| people
| from McMurdo to the South Pole Station and other research locations in
| Antarctica.
|
| Also by Googling we find that Bob Loewenstein is a Senior Research
| Associate
| at Yerkes Observatory
|
| >From New York Times, January 10, 1995 we read... Dr. Robert
| Loewenstein, an
| astronomer from the Yerkes Observatory of the University of Chicago,
| who is
| developing a system that will be used to operate, from a long distance,
| a
| whole family of advanced telescopes blooming this year at the South
| Pole.
|
|
| * * * Go to this page
| http://www.andrill.org/iceberg/blogs/luann/all.php#id2258259 * * *
|
| Scroll down until you get to the grid north map. Read the paragraphs
| that
| go with the map. Also notice that the map indeed puts north at the
| top,
| south at the bottom, east on the right, and west on the left.
|
| The map was made by Jessica Walker. It appears she has a PhD in GIS,
| and at
| the time she made the map she was working for Raytheon Polar Support
| Company
| in McMurdo Sound.
|
| The webpage showing the map is done by LuAnn Dahlman. Here is a blurb
| on
| her...
|
| LuAnn Dahlman
| NOAA Climate Program Office
| LuAnn Dahlman is a writer and editor for the Communications and
| Education
| group at NOAA's Climate Program Office. She earned a Bachelor's Degree
| in
| Geology at Arizona State University, and served as a practicing
| educator,
| K-12 curriculum developer, and workshop leader for inservice educators
| for
| more than 20 years. She has served as co-PI and Project Director on
| several
| NSF projects that encourage the use of technology and Earth science
| data for
| teaching and learning. During the 2006-2007 field season, Ms. Dahlman
| worked
| as a member of the ANDRILL project-ANtarctic geology DRILLing-
| recovering
| sedimentary rock records from beneath McMurdo Ice Shelf in Antarctica.
|
| * * *
|
| So there you have four people who have spent some time in Antarctica
| telling
| you that people "down there" use a grid-north map, and when looking at
| the
| map they consider the top as north, the bottom as south, the right as
| east,
| and the left as west. The person who drew the map is a GIS specialist,
| one
| of the persons who described the situation worked with Navy pilots in
| Antarctica, another is a PhD astronomer, and the fourth is a geologist
| working as a writer for NOAA.
|
| What more do you want?
|
|
|
|
|
| -----Original Message-----
| From: phys-l-bounces@carnot.physics.buffalo.edu
| [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of brian
| whatcott
| Sent: Thursday, February 16, 2012 12:28 AM
| To: phys-l@carnot.physics.buffalo.edu
| Subject: Re: [Phys-l] polar grid navigation
|
| On 2/15/2012 4:27 PM, Bernard Cleyet wrote:
| > On 2012, Feb 15, , at 07:11, chuck britton wrote:
| >
| >> At 9:58 AM -0500 2/15/12, Edmiston, Mike wrote:
| >>> So... after all the messages posted on this list-serv ridiculing
| the
| >>> news reports... it turns out the news reports were correct. If you
| >>> use the pseudo grid for Antarctica that navigators and scientists
| in
| >>> Antarctica are known to use (where grid north aligns with the prime
| >>> meridian), then Lake Vostok is indeed southeast of the south pole.
| >>> Actually I would call it "east southeast".
| > http://geology.com/world/antarctica-map.jpg
| >
| > http://en.wikipedia.org/wiki/Boxing_the_compass
| >
| > Yes, number 11.
| Oh my - given a whiff of polar grid navigation, which allows a
| direction
| indicator once set to hold a chosen course, I see we are leaping to
| (totally
| unwarranted) conclusions about the Vostok Lake lying to the south west
| of
| the pole.
| Grid navigation specifies courses 0 to 359 degrees grid..... not
| often
| thought of as sou,sou-east, by east and all that good stuff....
| And a polar projection does not constitute a polar grid for navigation
| in
| itself.....
|
| But why am I burning electrons so fruitlessly? :-)
|
| Brian W
|
|
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