Question

retrograde motion is explained by epicycles. the brightness of a planet increases when the planet is closest to earth. epicycles and deferents help explain planetary motion. retrograde motion is explained by the orbital speeds of planets. this model is sun - centered. this model is earth - centered. planets move in circular orbits and with uniform motion.

Explanation:

• Geocentric:
• In the geocentric model (Earth - centered), retrograde motion is explained by epicycles. Epicycles and deferents help explain planetary motion. Planets move in circular orbits and with uniform motion.
• Heliocentric:
• In the heliocentric model (Sun - centered), retrograde motion is explained by the orbital speeds of planets. The brightness of a planet increases when the planet is closest to Earth.

Answer:

• Geocentric: Retrograde motion is explained by epicycles. Epicycles and deferents help explain planetary motion. This model is Earth - centered. Planets move in circular orbits and with uniform motion.
• Heliocentric: Retrograde motion is explained by the orbital speeds of planets. The brightness of a planet increases when the planet is closest to Earth. This model is Sun - centered.