Circles...

Latitude: 66° 34.14’ S Longitude: 68° 21.71’ W
 
How does riding a stationary bike for 10 minutes wind up taking over an hour? Well, it happens when those 10 minutes are minutes of arc that are counting down on the GPS display on the TV monitor in the shipboard gym. As I start peddling on the now-familiar, frustratingly oh-so-stationary bike, we are approaching something amazing, to me at least—the Antarctic Circle, one of the 5 major circles of latitude on earth. On this trip, we have already passed 3 of the other 5—the equator, the line of latitude cutting the earth in half between the north and south hemispheres, as well as the Tropics of Cancer and Capricorn, the northern- and southernmost latitudes where the sun appears overhead at the June and December solstices respectively. The Antarctic Circle is the northernmost latitude where the sun can be seen overhead for 24 hours (on the December solstice, the first day of summer in Antarctica and the rest of the Southern Hemisphere). In general, I enjoy making up little rituals and challenges for myself, especially for anything I imagine to be a special occasion. I also love biking. So, when we are crossing a major line of latitude, I try to make an offering of sweat and effort on the bike. Maybe it’s for luck. Maybe it’s just to make crossing an invisible line on the globe feel more momentous. In any case, I find it very soothing.
 
For crossing the equator, I challenged myself to ride 100 nautical miles (about 115 standard miles) on the stationary bike. It took several hours and gave me ample time to acquaint myself with the definition of a nautical mile and some of the mental math around sea navigation. The globe is divided along lines of longitude and latitude, measured in degrees. A nautical mile is defined such that each degree of arc on one of these lines is 60 nautical miles apart. So, each minute of arc (as seen in the heading of these blog posts) represents 1 nautical mile (60 minutes in a…degree? perfectly sensible). My Antarctic Circle bike ride came at the end of a 12 hour shift collecting and packing samples. I was excited about crossing another major line but not about to make any major efforts on a stationary bike. I did a quick estimate for myself. We were close to 66° 23’ S latitude—about 10 nautical miles north of the circle (at 66° 33.805’ S), with the ship pointing almost due southwest at about 227° (or 47° off of a due south course), meaning we would be making a diagonal route to the circle that I could approximate as a right triangle with 10 nautical mile long sides… using Pythagoras’ theorem I know the remaining side—the course we would take to get to the circle—was about Ö200 or about 14 nautical miles. The ship travels at about 10.5 knots (nautical miles per hour) so(!) if I started then, I could expect to spend a bit less than an hour and a half on the bike before hitting my finish line. Just enough time for me to wind up exhausted and ready for a long rest at the end.
 
So I made my little solo ride. It was bizarre to me how quickly I got into the zone, in spite of the noticeable pitching and rolling of the ship. I busied myself at times checking my pace and imagining how funny it would be if I could ride an actual bike across the ocean. 10.5 knots (12 mph) would be a pleasant pace to bike for a long while. But our little ship has been doing it almost all the time for months now, day and night, rain, sleet, snow, and ice. Before I know it, we have crossed the circle. I dismount and stretch, finish my water and peek outside. The sea is gloomy and oddly free of much ice. I think about our ship, who never gets to rest until the job is done, and sheepishly duck off to shower and sleep, thankful for her tireless work, and the people around me who care for her.

James Townsend, Ph.D.
Postdoctoral Researcher
Marine Biological Laboratory