by astronomers of the day as zero longi-
tude. The observatory is now a public
museum located at the eastern edge of
London. It is a great spot for tourists,
who can find there a long strip of brass
that stretches across the yard marking
the “prime meridian.” Here it is possible
to straddle the line with one foot in the
Earth’s Eastern Hemisphere and the
other in the Western Hemisphere.How does one convert latitude
and longitudeto degrees from
readings containing degrees, minutes,
and seconds?
It takes simple mathematics to convert the degrees, minutes, and seconds of latitudes
and longitudes into degrees only. It helps to know that there are 60 seconds in one
minute, and 60 minutes in one degree. Therefore, to translate 65° 45' 36'' (also written
as 65:45:36) south latitude into degrees you would do the following calculation: 65
degrees (south makes the number “negative”) 45 minutes (1° /60') 36 seconds
(1'/60') (1°/60') 65.76° latitude.What are time zones?
Time zones are any of the 24 regions on the globe (loosely divided by longitude but
more erratic in their demarcations), which is divided according to the number of hours
in a day. Within each zone, all clocks are set to the same time. Time zones include the
international date line, an imaginary line of longitude generally 180 degrees east or
west of the prime meridian; the date becomes one day earlier to the east of this line.
Time zones are truly a product of mathematics. Initially, people used local solar
time, resulting in slightly different times between towns. With technology—especially
trains and telecommunications—more accurate timekeeping became a necessity.
Thus, time zones helped solve many of the problems by setting the clocks of a region
to the same mean solar time. The time zones made it easy for neighboring time zones
to be labeled “one hour apart.” Not that the system is perfect. The hour separation is
not universal, and because they often follow political boundaries, the shapes of the
time zones can be extremely irregular.How does one determine the distanceand amount of timea tripwill take?
There are several ways to determine the distance and amount of time a trip will take.
416 For example, if the traveler knows that his or her car travels 20 miles for every gallon