Calculating latitude and longitude at any time

In summary, latitude can be easily calculated by using the solar angle/time of day. Longitude can also be calculated by finding the time difference between your watch and GMT and then drawing a circle around that point on a map.
  • #1
z.js
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Calculating latitude at noon is easy: say I got ##73^o## on 6/20/2014
So, ##90^o-73^o=17^o##
then ##17^o+(\frac{1}{91})^o=17.01^o##(i forgot how to find N or S:biggrin:
Calculating longitude is also easy: First I set my watch to 12 00 at solar noon.
Then, I find the time difference between my watch and GMT--- say, 5h 37m 12s ahead
Since one hour is equal to 15o(##\frac{360}{24}##),
then: ##(5+\frac{37}{60}+\frac{12}{3600})hours*15 \frac{degrees}{hours}=84.3^oE##
...I know it is possible to do this any time, but how?:confused:
I suppose it is a totally different method. Does anyone know how to do this?

For example, I got: 46o/SUP] at 15 39, PST(Pacific Standard Time) on April 24th, 2016. How do I calculate latitude?

And how do I do longitude? Do I find the difference in celestial longitude(RA or Dec i forgot:redface:) , divide by 15 to find the time since solar noon and set my watch to 12 00 + difference? (perhaps it'll work... who knows!:tongue2:)
 
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  • #2
oops... please move this to 'Other sciences>>Earth'

Buhowyeesii ;)
 
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  • #3
z.js said:
Calculating latitude at noon is easy: say I got ##73^o## on 6/20/2014
So, ##90^o-73^o=17^o##
then ##17^o+(\frac{1}{91})^o=17.01^o##(i forgot how to find N or S:biggrin:
Calculating longitude is also easy: First I set my watch to 12 00 at solar noon.
Then, I find the time difference between my watch and GMT--- say, 5h 37m 12s ahead
Since one hour is equal to 15o(##\frac{360}{24}##),
then: ##(5+\frac{37}{60}+\frac{12}{3600})hours*15 \frac{degrees}{hours}=84.3^oE##
...I know it is possible to do this any time, but how?:confused:
I suppose it is a totally different method. Does anyone know how to do this?

For example, I got: 46o/SUP] at 15 39, PST(Pacific Standard Time) on April 24th, 2016. How do I calculate latitude?

And how do I do longitude? Do I find the difference in celestial longitude(RA or Dec i forgot:redface:) , divide by 15 to find the time since solar noon and set my watch to 12 00 + difference? (perhaps it'll work... who knows!:tongue2:)



I asked a sailor the other day. He said, shoot three stars at specific times and then look up the result in a book of tables. Surely there is more detail available out there under the heading of navigation.
 
  • #4
Well, I already know this way. What I meant is in the daytime and using the sun, chronograph and other things like that.
 
  • #5
Hornbein said:
Surely there is more detail available out there under the heading of navigation.
The exact way to do it is like this.
1. Find three or more brighter(and therefore more important) stars.
2. Measure the height of each star in at most two minutes with a sextant or something. Two minutes would give you plenty of time to measure and also, the amount of error is not so high.
3. Find the geographic positions(lat. and long. on Earth where the star appears overhead) of each star and mark those coordinates on a double map. (two identical maps joined together)
4. Draw a circle around each of the points with their radii according to the heights observed for each star.
5. The place where all the circles intersect is the approximate location of your ship.
:smile:
 
  • #7
z.js said:
I've already posted this somewhere else, but I would like some more answers to it.:smile:

https://www.physicsforums.com/showthread.php?t=760001

It's PF policy not to allow the same thread topic to be posted to multiple forums.

If you are interested in how to navigate and determine your position, read this article first:

http://en.wikipedia.org/wiki/Navigation

If, after reading the article above, you want all the gory details about the tools used in navigation, you can read the book "American Practical Navigator", which can be downloaded from this site (relax, Mentors, it is a government publication):

http://msi.nga.mil/NGAPortal/MSI.portal?_nfpb=true&_pageLabel=msi_portal_page_62&pubCode=0002

The whole book is 35 Mbytes, but you can download only the chapters of interest.

Nowadays, chronometers, sextants, almanacs, astrolabes, and all the other traditional navigational paraphernalia have been largely superseded by the Global Positioning System (GPS):

http://en.wikipedia.org/wiki/Global_Positioning_System

You can purchase a relatively inexpensive GPS receiver which can be used to tell your lat/long. position to within a few meters of your actual location. The better receivers can also determine your altitude w.r.t. sea level and speed.
 
  • #8
Calculating latitude by the solar angle/time of day must take into account the date or it will not be accurate.
GPS does provide great accuracy, but to rely on technology (and battery life for that matter) without self reliance as a back up plan is foolish, at least on blue water (IMNSHO).
 
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  • #9
SteamKing said:
Nowadays, chronometers, sextants, almanacs, astrolabes, and all the other traditional navigational paraphernalia have been largely superseded by the Global Positioning System (GPS):

http://en.wikipedia.org/wiki/Global_Positioning_System

You can purchase a relatively inexpensive GPS receiver which can be used to tell your lat/long. position to within a few meters of your actual location. The better receivers can also determine your altitude w.r.t. sea level and speed.

I just do not like GPSs. They give you your exact location, BUT to me I feel like a dummy, using that.
What I asked for was one that you could use your brain on.

I need to find lat. and long. at any time of a given day.
 
  • #10
Burnerjack said:
Calculating latitude by the solar angle/time of day must take into account the date or it will not be accurate.
GPS does provide great accuracy, but to rely on technology (and battery life for that matter) without self reliance as a back up plan is foolish, at least on blue water (IMNSHO).

Yes, I quite agree. :biggrin:
 
  • #11
z.js said:
I just do not like GPSs. They give you your exact location, BUT to me I feel like a dummy, using that.
What I asked for was one that you could use your brain on.

I need to find lat. and long. at any time of a given day.

Then I humbly suggest you download and start studying the American Practical Navigator and rounding up the required instruments.

The other systems for marine navigation, like LORAN-C or DECCA, have been decommissioned. Like it or not, GPS is used by the military to locate targets and navigate land vehicles, aircraft, and ships. It has superseded inertial navigation systems in the guidance of cruise missiles and ICBMs. You want to drop a bomb down a smokestack, it's going to have a GPS receiver attached to it. You want to go hiking in the woods, carry a GPS receiver.

And other countries are jumping on the band-wagon with competing systems. The Russians and Chinese have their own satellite-based systems similar to GPS, largely for military use, and the EU is reportedly planning on building its own satellite navigation system as well.
 
  • #12
SteamKing said:
Like it or not, GPS is used by the military to locate targets and navigate land vehicles, aircraft, and ships. It has superseded inertial navigation systems in the guidance of cruise missiles and ICBMs. You want to drop a bomb down a smokestack, it's going to have a GPS receiver attached to it. You want to go hiking in the woods, carry a GPS receiver.

And other countries are jumping on the band-wagon with competing systems. The Russians and Chinese have their own satellite-based systems similar to GPS, largely for military use, and the EU is reportedly planning on building its own satellite navigation system as well.
I was not so extreme as to that though... I will have a look at the book.:smile:
 

1. How do you calculate latitude and longitude at any given time?

To calculate latitude and longitude at any given time, you will need to know the time, date, and location of the point you are trying to determine. You will also need to have access to an accurate map or globe. Using these tools, you can use mathematical formulas and measurements to determine the latitude and longitude coordinates at any given time.

2. What is the difference between latitude and longitude?

Latitude and longitude are both measurements used to determine a specific location on Earth. Latitude measures the distance north or south of the equator, while longitude measures the distance east or west of the Prime Meridian. Latitude is measured in degrees, while longitude is measured in degrees, minutes, and seconds.

3. How does the Earth's rotation affect latitude and longitude?

The Earth's rotation affects latitude and longitude because the lines of latitude and longitude are determined by the Earth's axis of rotation. As the Earth rotates, the lines of latitude and longitude remain fixed in their positions, allowing us to accurately determine locations on the Earth's surface.

4. Can you calculate latitude and longitude without using a map or globe?

No, it is not possible to accurately calculate latitude and longitude without using a map or globe. These tools provide the necessary reference points and measurements needed to determine the coordinates of a specific location. Without them, it would be extremely difficult to accurately calculate latitude and longitude.

5. Why is it important to know how to calculate latitude and longitude at any time?

Knowing how to calculate latitude and longitude at any time is important for a variety of reasons. It can be useful for navigation, determining time zones, and tracking the movement of objects on Earth. It also allows us to accurately map and understand the Earth's surface and how it changes over time.

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