A discussion in one of my Virtual Class sessions about converting and rounding geographic coordinates led to this question from a student: “Who needs to deal or work with seconds?” A non geography major (and perhaps many geography majors) do not have a conception of arc or global coordinate distance, perhaps because this is (slightly) an abstract conception.
Remember the ‘69 mile’ rule? This is an easy way to convey the impression of global distances and Great Circle routes. A Great Circle is any circle that would use the center of the Earth as the radii point. The Equator is a Great Circle. A (one) meridian is half a Great Circle. A Great Circle is the shortest distance between any two points. A Great Circle bisects the Earth into two equal pieces (“bisect” is the clue). Assuming the 69 mile rule, students can calculate the Earth circumference, and I have them do that on quizzes. A complete circle is 360 degrees (such as a Great Circle). If we assume 69 miles per degree, then 69 x 360 = Earth circumference (with all due respect and apology to those geodesy scientists who know this is a gross exaggeration.). How does that equate into minutes? Seconds?
69 miles = one degree, then
1 minute = 69 miles / 60 minutes = 1.15 miles
1 second = 1.15 miles / 60 seconds = .019 miles, or better 101.2 feet
In a rough sense, if I was lost in the ocean with a GPS receiver that showed degrees-minutes-seconds, I could convey my location roughly within a 100 feet box to my potential rescue helicopter. Consider storms, waves, tides, currents, fog, rain, snow, sleet, and nighttime. How safe do you feel? Ah, when seconds count! Temporal and spatial!
GPS shows even greater (decimal place) accuracy, which makes it an important tool for surveyors and engineers for construction, military types for accurate destruction, and geography instructors for regurgitation.
– S. Robinson
Geography plays a much bigger role in our lives than we sometimes realize. Every day, we make decisions based on how to get from one location to another – and it becomes even a greater concern when we take into account our mode of travel because geography is essentially mathematics:
Distance = Time + Cost
So we make location decisions based on our ability to reduce the variables Time and Cost to affect the outcome Distance. How far do we drive to work, school, or recreation is part of our daily interaction with geography.
The horrible tragedy of the Malaysia Airlines Flight 17 that was shattered in Eastern Ukraine along with as many as 300 lost souls is an example of how geography matters. If one wants to avoid large land areas, this will increase distance – and increase our variables of time and cost. Airlines must consider profit and customer convenience (time in-flight) when plotting courses between locations. Weighting the consequences of a chance encounter with a Russian-made Buk surface-to-air missile is not often part of the equation in the consideration of flight paths.
Mathematically, our old friend Pythagorean, working with Euclidean geometry, figured out the square of the hypotenuse is equal to the sum of the squares of the other two sides of a right triangle. In simple geographical terms, by traveling the hypotenuse, one moves over a much shorter distance (975 miles) as opposed to the combined distance of legs a + b (1240 miles). Time + Cost are reduced considerably:
This is not much solace for the poor folks who perished in this catastrophe. An international act of intentional terrorism or a mistaken identity and nervous trigger finger will undoubtedly be played out in the media for years. What is sure is that geography is always an issue that needs further consideration and appreciation – because geography matters.
“Then my spirit will haste to her resting-place, As she lies on the wreck-strewn floor;
I will shelter my love in a close embrace, Till the sea shall be no more.”
Danske Dandridge, Lost at Sea, 1900