Aristarchus measured the angle between the Sun and the Moon when exactly half of the Moon was illuminated. He found this angle t
o be A greater than 90 degrees. B exactly 90 degrees. C less than 90 degrees by an amount too small for him to measure. D less than 90 degrees by an amount that was easy for him to measure.
when the Sun illuminates half of the Moon it must be at 90°
Explanation:
The Moon has a circular motion around the Earth and the relative position of the sun, the earth and the moon create the lunar phases.
For this case when the Sun illuminates half of the Moon it must be at 90°, this angle changes with the movement of the moon, it is zero degree for the new moon and 180° for the full moon
