One of my earliest posts was on the time differences between Santiago and Winston-Salem (or the east coast generally).  I thought that would be a useful bit for people to know what time it was where I am, especially if they want to talk to me or have me attend meetings and whatnot.  Plus, there are some quirks.  Were it not for the collected wisdom of politicians, time would be a simple affair.  Alas, time is not a constant on planet earth and there will be three different time differences between folks at home and me and the students while we’re here.  If you missed it and care, check it out.

If you don’t, don’t ask me what the time difference is.

Anyway, tomorrow Mary and I fly further south, as far as you can go without a government contract, to Punta Arenas which sits on the Straits of Magellan.  We’ll see some penguins and do some hiking and, importantly for me now, experience some chilled air.

This has me thinking about the round world we live on and the metric by which we measure north and south.  I’d guess/assume/hope that everyone reading this agrees that the Earth is round, an oblate spheroid as they say.  I’d further guess most folks know generally that this means different stars are visible from Santiago than from Winston-Salem.  Basically, you can only ever see half the universe from any one point on Earth.  A good bit of that visible from Winston is visible from Santiago but it’s shifted north while a lot of stuff invisible from Winston is now visible.

It also means that WE are actually pointed differently.  Winston-Salem is at latitude 36 degrees N.  It is 36 degrees toward the north pole from the equator or, equally, 54 degrees toward the equator from the north pole.  I won’t go into latitude, you guys get latitude.  The celestial equivalent of latitude is a measure called Declination and it does the same thing.  A star at declination 36 degrees N declination (roughly, the bright summer star Vega) is 36 degrees toward the north celestial pole (Polaris, the North Star, more or less) from the celestial equator (an imaginary line that extends out from Earth’s equator to infinity).

So, when you stand at attention on level ground in Winston-Salem your head points at 36 degrees N declination.  When I do the same here in Santiago, my head points at 33 degrees S declination (roughly, the star Shaula, the Scorpion’s stinger).  Fine and dandy.

But that means that you and I, both standing at attention on level ground are pointed in wildly different directions.  Santiago is fairly close to straight south of Winston so we can ignore that slight (about 10 degree) difference and create the following picture.  It shows two guys, Santiago and Winston, and how they are pointed when standing at attention in Santiago and Winston-Salem, respectively.  North is to the right.

latitude-declination

(That’s right, I can draw guys in ChemDraw).

Go outside and stand at attention.  I assure you, I’m doing the same at the same moment.  That’s us.  The longitude difference mentioned in the time zone piece means that, really, I’m twisted about 10 degrees to the east from you but the N/S angle is correct.

I’m sure you’re blown away by this but a 69 degree angle is hard to keep in mind walking around.  That brings me to Punta Arenas.  When we’re in Punta Arenas, standing at attention, we’ll be pointed at 54 degrees S declination (roughly the N tip of the Southern Cross).  Go ahead and do the math.

When I am standing at attention in Punta Arenas and you stand at attention in Winston-Salem, you will be perpindicular to me.  That is, you’ll be laying on the ground (or vice versa).

If you’d like a more picturesque version, anytime you’re standing up in Winston, the penguins living around Punta Arenas or oriented the same as your floor.

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3 thoughts on “Give a little latitude

  1. This one truly blew my mind. In my momma eyes I picture my child about to fall off the earth and I can’t help him. Just weird weird weird Not that I can’t help you You are way beyond needing that but thinking about when I stand up you and the penguins are laying down. Now that’s weird

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