The Earth is farther from the Sun, so the light is less intense. The Sun is at a lower declination, so the length of the day is shorter. The Sun travels through a larger amount of the Earth's atmosphere due to its lower position in the sky. During a planet's retrograde motion, it appears to a. become brighter and dimmer. The diameter of Earth was first determined by a. using simple geometry and measuring the Sun's position.
Retrograde motion occurs when a. the planets move on epicycles.
The shape of the Earth was first determined by a. sailors in the last half of the 15th century. One of the main reasons ancient astronomers did NOT believe the Earth orbited the Sun was a. the changing seasons. If you increase the distance between the Sun and the Earth by a factor of 4, the force of gravity between the Earth and the Sun would a. increase by a factor of 4. He made the most accurate naked eye observations of planetary positions ever made. He constructed a model of the solar system with the Sun at the center.