The Antipode...finding summer all year long!

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Here's a map and method to find out what's on the opposite side of the world at a particular location.

What is an antipode?

Any point on the surface of a sphere, in this case the Earth, that lies diametrically opposite from a given point on the same surface, so that a line drawn between the two points through the center of the sphere forms a true diameter (e.g. line through the Poles of a Sphere). The Antipodes islands of New Zealand, in the South Pacific, are named after this geodetic feature because of there near opposite location to London.

Calculating the antipodal point for any point on the Earth's surface can be summarized in the following Python code:

The method using decimal degrees:

Take the latitude and convert it to the opposite hemisphere. This is done by multiplying by minus 1 (e.g. -x * -1 = x).

The longitude is calculated by taking the maximum possible longitudinal value and subtracting the input longitude value. The if statements allow for "which way round the Earth" the calculation is conducted this is important because the values are bounded to +180 and -180. For example a longitude of -10 has an antipodal location of ((-180) - (-10))*-1 = 170.

# Original latitude and longitude values in Decimal Degrees
Latitude =  33.918861
Longitude = 18.4233

# Convert latitude to opposite hemisphere (e.g. −x* −1 = x)
AntiLatitide = Latitude *-1

print "Antipodal Latitude: " + str(AntiLatitide)

# Convert Longitude to opposite hemisphere (e.g. (180 - x)*-1 = y)
# Note this binds the maximum values to be -180 and 180 degrees
if Longitude > 0:
    AntiLongitude = (180 - Longitude)*-1
elif Longitude < 0:
    AntiLongitude = (-180 - Longitude)*-1

print "Antipodal Longitude: " + str(AntiLongitude)

A result...the Antipodal point of London

Combining the above code with the XY to Line tool allows me to construct a geodesic line joining the two points thus producing this result!

A free map calculating the antipodal point of any location:

http://www.freemaptools.com/tunnel-to-other-side-of-the-earth.htm