Understanding the Shorter Route in the Southern Ocean – Part I

Having made a comment in one of our previous articles to which one of our Readers found quite humorous, and critically responded to, it is obvious that he missed the point of the article. This issue regarding the distance around the globe in the Southern Ocean, which is important enough to keep responding to whenever it is challenged with inaccurate or erroneous comments and information.
    In this case, the distance around the globe at the equator where some theorists want to Lehi to cross, is of considerably longer than around the Southern Ocean, which we propose since that is where the winds and currents flow, and is of great interest and importance to the sea route Lehi took to the Land of Promise.
    Often we receive comments, critical of the South American Land of Promise since it is not in the mainstream of most theorists’ thinking, and just as often, those comments are based on unknowledgeable and completely erroneous ideas. Consequently, we reply with a detailed answer for the benefit of those interested.
    The reader’s comments follow:
• Reader: "You wrote: The world is round, and like a ball, the closer one comes to either pole, the shorter the circumference until it [the circumference] is zero." LOL! You flunked geometry. A circumference of zero for a globe. Ha ha ha.”

The parallel latitude circle around the globe is the longest at the equator, and higher and lower latitude circles shorten as they move toward either pole

Response: Glad you enjoyed the laugh. The term “zero” was used more or less as a euphemism to avoid having to explain in detail what was being discussed (which we will now do below)—“zero” made the point quite well earlier in stressing understanding that the distance around the globe or planet is considerably reduced as one travels toward the poles (higher latitudes). In fact, a degree of longitude is widest at the equator with a distance of 69.172 miles; however, “the distance gradually shrinks to zero as they meet at the poles” (Matt Rosenberg, “What Is the Distance Between Degrees of Latitude and Longitude?” Navigating the Earth, One Degree at a Time, ThoughtCo., Dotdash Publishing, 2018).
    In addition, after two years, a geoid map was produced by the European Space Agency GOCE satellite showing that the Earth is not really a sphere (or globe), because the gravity is not uniform, with the shape of the planet being affected everyday by such factors as wind, currents and tides, showing that such gravity is higher in the north, such as in Iceland, than say in Arabia or India in the south.
    It should also be noted that the mean radius of Earth is 3,959 miles, with the planet’s rotation causing it to bulge at the equator. Earth’s equatorial diameter is 7,926 miles, but from pole to pole, the diameter is 7,900 miles. At the same time, the circumference of Earth at the equator is about 24,902 miles, but from pole-to-pole—the meridional circumference—Earth is only 24,860 miles around.
    This shape, caused by the flattening at the poles, is called an oblate spheroid, and thus the Earth’s equatorial circumference is greater than its polar circumference—that is, the circumference of the Earth at the 60^th parallel north or south (60º north/60º south latitude) is approximately half as long as the Equator. This means that any travel, moving east or west, by ship or otherwise across the Pacific at the equator, would take twice as long as, say, a voyage taken at 60º south latitude.

The closer one gets to the poles, the shorter the distance around the world—if one traveled to either pole, the latitude would be 90º—since each parallel of latitude represents about 69 miles apart from one another, the distance around the 90º latitude would be negligible relating to actual, measurable distance

Consequently, as a ship takes an east-west route at higher latitude, the ship travels a shorter distance than at lower latitudes, even to Latitude 0 at the equator. This is the principle that makes the Southern Ocean such a viable racing route for International Sailing races (Vandée Globe; Volvo Ocean Race; Southern Ocean Dash; Global Ocean Race, etc).  The fact that the winds and currents also move faster in the Southern Ocean is another reason in using this ocean for races.
    Thus when you stated in your critique of our article, that it would be longer going the Southern Ocean to South America, than the Atlantic Ocean to Florida, you were not correct. In addition, it is interesting that you did not bother to react to that concept of the Southern Ocean being such a shorter distance around the globe, which made Lehi’s trip much shorter in distance and time via the Southern Ocean showing that route would have been far better than the one you champion moving north to south along meridians.
• Reader: “I assume you meant the "Great Circle."
Response: No, we did not. The “Great Circle” is any circle drawn on a globe or sphere with a center that includes the center of the globe. This means that the only latitudinal line that is a “great circle” is the equator. Of course, all longitudinal lines are “great circles.” Further, great circles are easily based on the lines of latitude and longitude, with each longitude, or meridian, being the same length and representing half of a great circle. This is because each meridian has a corresponding line on the opposite side of the Earth. When combined, they cut the globe into equal halves, representing a great circle. For example, the Prime Meridian at 0° is half of a great circle. On the opposite side of the globe is the International Date Line at 180°, which also represents half of a great circle. When the two are combined, they create a full great circle which cuts the Earth into equal halves.
    However, lines of latitude, or parallels, characterized as a great circle is only the equator because it passes through the exact center of the Earth and divides it in half. Lines of latitude north and south of the equator are not great circles because their length decreases as they move toward the poles and they do not pass through Earth's center. As such, these parallels are considered small circles.
    Therefore, our article was not referring to great circles, but to the latitude lines on a globe decreasing in length as the latitudes get higher (approaches the poles).
• Reader: “That's easy for jet planes to travel, not so much for ships.”

Longitude Lines merge at 90º as opposed to Latitude Lines which are always the same distance apart. It is obvious from the right side globe that the horizontal distance between the two Longitude Lines is different the further one moves away from the equator. The a ship sailing in the Southern Ocean travels a far shorter distance than one traveling longitudinal north and south up the Atlantic

 

Response: Air miles and distance traveled are based upon an entirely different criteria—planes fly a direct route, but also do so in a circular manner in the sky from takeoff to landing. On the other hand, a ship sails on the surface of the planet, and is both a direct horizontal and vertical route. In addition, on the surface of the planet, while degrees of latitude are parallel so the distance between each degree remains almost constant at abut 69 miles, but since degrees of longitude are farthest apart at the equator and converge at the poles, their distance varies greatly. As an example, the distance between 30º longitude and 60º longitude at the equator is 2,075.16 miles.
    From the area of Oman (Salalah) where Nephi’s ship sailed, through the sea of Arabia, the Indian Ocean into the Southern Ocean (a gradual arc from west to east in the direction of the several gyres and currents in those areas), there is an open ocean with no obstacles. Sailing as Nephi stated, “driven forth before the wind” is a direct route, again, taken by numerous ships, beginning with the early trading vessels, then the clipper ships and today with International racing regattas, and easily mapped and sailed and have been for generations.
(See the next post, “Understanding the Shorter Route in the Southern Ocean – Part II,” for more of the critique of a Reader and our responses regarding sailing through the shorter route of the Southern Ocean for Lehi)