Figuring Longitude Antipode

[+curious4cache]

I know I need to subtract E 98* 41.900 from 180 degrees to get the east/west antipode.

I'm doing something wrong though...

I've read Google articles, but can't find anything specific enough. Their examples only use degrees.

I found an antipode calculator site and either my dinosaur computer can't handle it, or I'm not entering the coordinates in the proper format. It keeps giving me an error message.

 

Any help would be appreciated, I need an education on understanding coordinates better!

 

TIA

[+tomfuller & Quill]

someone will probably Markwell this, but this is the way i figured it out. First divide the minutes (including decimal) by 60 to get decimal minutes. 41.9 divided by 60 = .69833333.. subtracting 98.69833333 from 180=

81.301666667. Thus the antipode of E98*41.900 is W81* 18.100.

Subtract the latitude from 90.000 to get the antipode latitude. Ex. S35* antipode = N55*

[+Cardinal Red]

Part of the response by tomfuller & Quill is correct.

 

It is easier to convert to decimal degrees to explain this.

 

41.900 Minutes = .69833 Degrees (The calculation is 41.9 divided by 60).

 

Thus 98 Degrees, 41.900 Minutes = 98.69833 Decimal Degrees

 

180 - 98.69833 = 81.30166 Degrees (The antipode).

 

Since the original 98.69833 was East, The antipode of 81.30166 will be West.

 

To convert back:

 

.30166 Degrees times 60 = 18.0996 Minutes (Rounds to 18.100 Minutes)

 

That makes the antipode 81 Degrees, 18.100 Minutes West.

 

That should make sense, because 60 Minutes minus 41.900 Minutes = 18.100 Minutes

 

180 minus a West Longitude = an East Longitude antipode

 

180 minus an East Longitude = a West Longitude antipode

 

But: ..............

 

A North Latitude converts directly to a South Latitude antipode

Example: 75 Degrees, 45 Minutes North = 75 Degrees, 45 Minutes South

 

A South Latitude converts directly to a North Latitude antipode

Example: 55 Degrees, 20 Minutes South = 55 Degrees, 20 Minutes North

 

Edited: I somehow used the wrong degree number instead of the 98 Degreees you used in your example. I have updated my math to use 98 Degrees in my Longitude calculations.

Edited March 9, 2008 by Cardinal Red