Retrograde Motion and Heliocentric Model

Who was the first to propose that the Sun is the center of the solar system?

• Ptolemy

• Aristarchus

• Copernicus

• Bruno

Which model of the solar system remained dominant for centuries after Aristarchus's proposal?

• Heliocentric model

• Geocentric model

• Epicyclic model

• Copernican model

Who perfected the geocentric model in 2nd century Egypt to explain phenomena like retrograde motion?

• Aristarchus

• Copernicus

• Ptolemy

• Galileo

What is retrograde motion?

• A planet appearing to travel faster than usual

• A planet appearing to travel in the opposite direction

• A planet appearing to stop moving

• A planet appearing to change color

In the heliocentric model, what causes retrograde motion?

• The planet changing its orbital direction

• The Sun's gravitational pull

• Earth passing the planet in its orbit

• The planet's epicycles

How did Ptolemy explain retrograde motion within the geocentric model?

• By suggesting planets moved in straight lines

• By proposing planets moved on smaller circles called epicycles

• By stating planets occasionally stopped moving

• By introducing elliptical orbits

Who was the first to suggest a heliocentric model since Aristarchus, demonstrating it solved problems with the geocentric model?

• Galileo Galilei

• Johannes Kepler

• Nicolaus Copernicus

• Isaac Newton

Why is the apparent shift in the position of stars (parallax) so tiny?

• Stars are too small to observe

• Earth's orbit is too small

• The stars are at immense distances

• Telescopes are not powerful enough

What mathematical tool is used to find the distance to a star using its parallax angle?

• Algebra

• Calculus

• Geometry

• Trigonometry

What radical idea did Giordano Bruno propose based on the heliocentric model?

• That Earth was flat

• That the Moon was a planet

• That other stars could be suns with their own planetary systems and living creatures

• That the universe was static and unchanging