Which significant observation led the Greeks to accept the idea that Earth was a sphere?
A)The shape of the darkening across the Sun's disk during a solar eclipse always appeared circular.
B)The shape of Earth's shadow on the Moon during a lunar eclipse was always circular.
C)The Sun disappears below one horizon each day and reappears above the opposite horizon.
D)The shape of the eclipse shadow on Earth during a solar eclipse was always circular.

Question

Quizplus · Accepted Answer

The observation that the shape of Earth's shadow on the Moon during a lunar eclipse was always circular led the Greeks to accept the idea that Earth was a sphere. This is because only a spherical object can cast a circular shadow from any angle.

Which Significant Observation Led the Greeks to Accept the Idea