Question

which describes one way that aristarchuss explanation of the movement of objects in the sky was different from other scientists earlier explanations?
he discovered venuss phases.
he argued that earth rotates on its axis.
he explained the concept of retrograde motion.
he described the epicycles of the planets in the sky.

Explanation:

Aristarchus of Samos was an ancient Greek astronomer known for proposing a heliocentric model. Earlier prevailing models were geocentric, and a key difference in his work was arguing Earth rotates on its axis (and orbits the Sun). Venus's phases were observed by Galileo, retrograde motion was explained before Aristarchus, and epicycles were part of geocentric models to explain planetary motion, not Aristarchus's work.

Answer:

B. He argued that Earth rotates on its axis.