Travel Reference
In-Depth Information
For example, the time gap between Greenwich and New York City is five hours,
which translates into a longitudinal difference of 75°. Equipped with an accurate
timepiece set to Greenwich Mean Time, sailors could figure out their longitude by
comparing sunset time at their current position with sunset time back in Greenwich.
Notice that both approaches use Greenwich as a baseline—either on an astral
map or on a clock. That's why, to this day, the prime meridian and official world
time are both centered in this unassuming London suburb.
As you hike up, look along the observatory's roof for the red
Time Ball
(also visible
from the Thames), which drops daily at 13:00.
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Royal Observatory Greenwich
Located on the prime meridian (0° longitude), the observatory is famous as the point from
which all time is measured. The observatory's early work, however, had nothing to do with
coordinating the world's clocks to Greenwich Mean Time (GMT). The observatory was
founded in 1675 by King Charles II for the purpose of improving navigation by more ac-
curately charting the night sky. Today, the Greenwich time signal is linked with the BBC
(which broadcasts the famous “pips” worldwide at the top of the hour). A visit here gives
you a taste of the sciences of astronomy, timekeeping, and seafaring—and how they all
meld together—along with great views over Greenwich and the distant London skyline.
The Royal Observatory grounds are made up of the observatory (with the prime meridian
and three worthy exhibits), the Weller Astronomy Galleries, and the Peter Harrison Plan-
etarium.
If your only interest in the Royal Observatory is the famous prime meridian line, you
can go through the iron gate near the entrance for a free, more simplistic (and signific-
antly less crowded) display of the prime meridian. Under the analog clock just outside the
courtyard, see how your foot measures up to the foot where the public standards of length
are cast in bronze.
Observatory:
£7, £11.50 combo-ticket with planetarium saves money if you visit
both; daily 10:00-17:00, later in summer, last entry 30 minutes before closing; audioguide-
£3.50, 1 hour.
Weller Astronomy Galleries:
Free, daily 10:00-17:00, last entry 30 minutes before
closing.
Peter Harrison Planetarium:
£6.50, £11.50 combo-ticket with observatory;
30-minute shows generally run every hour (usually Mon-Fri 13:00-16:00, Sat-Sun
11:00-16:00, fewer in winter). Confirm times in advance by phone or online, or by picking
