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TerraLens

Case study · US

US lower-48 time zones

Eastern to Pacific

Four civil zones across about 60° of longitude, with jogs for state lines. The terminator ignores the jogs.

A continent sitting on a sphere, not stretched on a rectangle.
A time zone is a political cut of a spinning sphere.NASA, public domain

Locator · OpenStreetMap / OpenFreeMap · 39.80°, -98.60°

Noon in Boston is still morning in Seattle because the planet has not finished that 15° × 3 turn. Eastern, Central, Mountain, Pacific are civil bands. They jog around cities and state lines. The Sun does not.

The rotation lab’s time-zone overlay is this. Toggle it on, then off. The terminator is the machinery. The colours are the timetable.

Open this state in the lab

Exam-style question

If solar noon has just reached New York, about how long until solar noon in a place 45° of longitude further west?

Teacher hint: 45/15 = 3 hours.

Process labs

Earth rotation and the terminatorGraticule and coordinates

Sources

  • NIST / USNO