Directions, poles and time
Meet north, south, east and west, choose a clock at the pole, then try a walk that brings you back to the beginning.
Four directions help us find our way
North
On a north-up map, north is at the top. True north follows a meridian toward the geographic North Pole.
This is a north-up map diagram, not a sensor showing which way your device is facing. A magnetic compass follows Earth’s magnetic field; magnetic north and geographic north are different.
USGS: true, grid and magnetic north ↗What time would you use at the North Pole?
All lines of longitude meet at the geographic North Pole. Longitude alone cannot select a unique local clock there: a group must choose a practical time reference. This lesson uses UTC, at offset +00:00.
For everyday clock labels, GMT means the same zero offset as UTC. UTC is the international time reference; GMT also has historical meanings connected to Earth’s rotation. This does not mean every polar expedition must keep UTC.
Clock choices at a pole are practical, not a special property of Earth’s shape. For example, the U.S. Antarctic Program’s South Pole station has used New Zealand time to coordinate operations. That does not make it local solar time.
Sources: NIST: UTC and GMT, USAP: polar station time conventions.
South, east, north… back to the same pole!
Start at the geographic North Pole. Walk 100 miles south, then 100 miles due east along that latitude, then 100 miles north. You return to the North Pole.
Zoomed-in polar cap
A flat grid with fixed directions
At the North Pole
Latitude 90°N. Longitude has no unique value at the pole.
Every initial direction along the surface is south. We choose one meridian for the first leg.
Each leg is 100 miles (about 161 km). After the first leg you are near 88.553°N. “Due east” follows a latitude circle, not a great-circle route with only an initial eastward bearing. True geographic directions are used; this is not a magnetic-compass navigation plan on drifting Arctic ice.
What does this puzzle show?
Meridians converge on a sphere, so “north” changes direction as you move around the pole. The comparison illustrates spherical geometry versus a flat grid with fixed directions. It is a useful model lesson; the walk alone is not a complete proof of Earth’s shape. Independent measurements, geodesy and observations from space establish that Earth is approximately spherical and slightly flattened at its poles.
At the South Pole the situation is reversed: every initial surface direction is north. The geographic poles are different from the wandering magnetic poles.
Read USGS on meridians and true north and NOAA on compass directions near magnetic poles.
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