Question

Which hypothetical scenario would result in the moon not having different phases?

A he moon takes twice as long as it does now to orbit the earth.

B Earth takes twice as long as it does now to orbit the sun.

C Earth has two moons.

D The moon always stays in one position relative to the earth and sun

Answer 1

D) the moon would stay in one position relative to earth and sun

if the moon were always opposite the sun we would always see a full moon

The sun rotates about the earth once every 366 days (if the earth did not rotate we would see a complete rotation of the sun every 366.25 days)

In one year there 365.25 rotations of the sun about the earth

366.25 days for the earth to rotate - 1 day because of the earth about the sun = 365.25 the length of a day that we observe

(Note the difference between a "sidereal" day and an "astronomical" day)