NYT Story

Southern California and far-away places. Hiking, wildlife, cycling etc.

Re: NYT Story

Postby Hikin_Jim » Thu Jun 02, 2016 9:52 am

zippetydude wrote: They always mention that you need to know how to use a map and compass...um, this may sound dumb, but as long as you know the top of the map points north, the needle on the compass points north, and the contour lines on a topo indicate elevation change, isn't this a self-taught sort of skill? The first time I ever went backpacking my dad and I used both for navigating, neither of us ever having taken a class or been instructed in it.

Actually, a compass doesn't point north; it points at magnetic north. It points, in Southern California, about 12 degrees of arc east of north. Now, 12 degrees may not sound like a huge amount, but consider the following example: A day hiker typically walks about 3 mph on good trail in relatively moderate terrain (i.e. not the Marion Mountain Trail). :) Therefore, a one hour walk following a compass in S. California would result in one being about 0.6 miles east of where one intended. That's about 2/3rds of a mile. And for Zippettydudes who go, say, 5 mph, the error is just over a mile. "Missed it by a mile" isn't exactly precise navigation you know. ;) The further north you go, the more pronounced the error is. There is one story, famously, of a polar exploration group that headed for two days in the wrong direction due to miscalculating the difference between compass north (magnetic north) vs. true north.

Neither does a map point to north. Due to the nature of Mercator Projection, which takes a spherical globe and breaks it up into rectangular flat maps, north is always a bit distorted. The impact is not as great as with compass error, but it is there. So, there's a bit more knowledge involved here.

In my experience as a map reading instructor in the Army, some people get it, and some people don't. There are some people for which this whole map thing makes no sense whatsoever, and they struggle though they are intelligent people in other respects.

zippetydude wrote: We just looked at it, interpreted it, and made our way around with clarity and ease.
Well, don't try that in Kansas -- or in the deep woods of Appalachia. You'd better have a bit more technical skill there, though, as you say, you can reason this stuff out, or at least some people can. This poor woman sounds like someone who just didn't have that ability.

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Re: NYT Story

Postby zippetydude » Thu Jun 02, 2016 11:58 am

Here you go Ed:

Imagehow-to-find-the-north-star by zippetydude


If you can find the Big Dipper, when you connect the last two stars in the dipper they point straight to the North Star. It's just the next bright star, so it's not tricky or confusing. Try it out tonight - you will forever be able to amaze your friends by having this uncanny, true outdoors-man type of skill!

Polaris is interesting in other ways besides being the North Star. It is a three star system with one supergiant that is 50x the size of the sun and two smaller companions. There is some evidence that it may actually be a five star system, which would make it popular on ebay. Sorry, gettin' carried away there.

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Re: NYT Story

Postby Ed » Mon Jun 06, 2016 9:06 am

I saw it! I saw it! Last night! Well, I cheated like hell. Studied Zip's diagram, researched a UCLA webpage on the subject, knew which direction was north to begin with, etc. But give me a break, I have a tree in the way in my back yard. Thanks for the diagram and encouragement Zip, I've remedied one of my many lifelong deficiencies.

P.S. I have a neighbor who has a personal observatory at his second home in the high country of Colorado. When I told him I could not even find the North Star in the sky (but once had a job which occasionally required me to design spacecraft trajectories), he smiled and recommended an app. I had to tell him I had a dumb phone.
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Re: NYT Story

Postby Hikin_Jim » Mon Jun 06, 2016 9:32 am

Ed wrote:I told him I could not even find the North Star in the sky (but once had a job which occasionally required me to design spacecraft trajectories), he smiled and recommended an app. I had to tell him I had a dumb phone.
:lol: :lol:

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Re: NYT Story

Postby David W » Mon Jun 06, 2016 11:10 am

I'm no expert, but I cannot fathom getting lost like that. The sun rises in the east and sets in the west. Pick a direction and go, morning and evening...why on earth would you just park and wait to die? Climb a tree or a mountain and look around...
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Re: NYT Story

Postby zippetydude » Mon Jun 06, 2016 3:20 pm

Awesome Ed! I'm impressed that you actually went out and did it. If you go out tonight and look, it won't even be a challenge. How cool is that?

BTW, if you try to make out the Little Dipper you will probably have a bit of trouble. Some of the stars that make up the constellation are on the dim side. You can remedy this by looking slightly to the side of where the star actually is...and it will suddenly appear. This is called "averted vision".

The reason it works is that there are two kinds of light sensing cells in the retina - rods and cones. Rods are highly sensitive but see only black and white. Cones are endowed with the ability to distinguish color, but this comes at a cost - they are not as sensitive as rods. The focus of your gaze is projected onto the center of the retina, and because this is the most crucial information (since you have chosen to focus on it) it turns out that the additional information provided by color is more valuable in things you focus on than additional sensitivity. Your peripheral vision, which does not serve to add details but instead provides great sensitivity to change and motion, is packed with rods. So, when you look slightly to the side of the star, the light does not land on the cones in the center, it hits the more sensitive rods, which is why it suddenly appears. If you then try to look directly at the star, it will disappear again. It is a strange experience, but it does work. Anyway, congrats on gaining a new skill!

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Re: NYT Story

Postby Ed » Tue Jun 07, 2016 11:54 am

I did have trouble making out the Little Dipper. Rods and cones? The first reading made my head spin, but I think I understand after a second reading, and will give it a try.
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