- The earth rotates about its axis once each day, creating day and night.
- Which way does it rotate?
- A traveler flies from Tokyo to San Francisco, leaving Tokyo at 9 pm
Sunday evening, just two hours after sunset. While he sleeps, the sun
rises. He arrives in San Francisco. The clock at U.S. Customs says 1 pm.
What day is it?
Structure of the reasoning so far:
We have made a model (or a theory).
We deduce consequences that can be tested by observation.
- Earth rotates counterclockwise as seen from the north.
- Earth revolves around the sun counterclockwise as seen from the north.
- Earth's axis is tilted.
- Day and night.
- Height of the sun above the horizon at noon.
ASTR 121 Home
Davison E. Soper, Institute of Theoretical Science,
University of Oregon, Eugene OR 97403 USA