Lost at Sea: The Search for Longitude
You're invited on a transatlantic cruise aboard an
oceangoing yacht, the Miss Adventure, leaving from
England. Soon after setting sail, you encounter storms that
last for weeks. Then a devilishly thick fog envelops the
ship for several days. When the fog finally lifts, the sun
is at its apex, and a speck of land is faintly visible on
the horizon. "Land ho!" calls the lookout. The captain
determines quickly with his sextant that the ship is at
latitude 42 degrees north, but then discovers to his horror
that his chronometer has stopped. "Oh no!" he shouts, "Where
are we?" Thinking fast, you glance at your super-accurate
watch, which is set to Greenwich time. It reads 4:40 p.m.
Knowing that Greenwich time is the time at the prime
meridian of the world, which is 0 degrees longitude, you
perform a quick mental calculation and check the map. "No
problem, Cap'n," you call out confidently. "That land is...
(HINT: The Earth rotates in an easterly direction at a rate
of about 15 degrees per hour, or 5 degrees every 20
minutes.)
(ANOTHER HINT: When the sun is at its apex, it's as high in
the sky as it's going to be that day. That means it's noon.)
A.) Havana!" (longitude: about 82
degrees west of Greenwich)
B.) Chicago!" (longitude: about 88
degrees west)
C.) Tashkent, Uzebekistan!" (longitude:
about 70 degrees east)
D.) Cape Cod!" (longitude: about 70
degrees west)