Ptolemy perfected the _________ model of the universe

• heliocentric
• flat
• spherical
• geocentric

Retrograde motion is when a planet appears to

• move in a circular path
• stay stationary in the sky
• accelerate away from the sun
• move backward in its orbit

Ptolemy proposed the idea of _______ to explain apparent retrograde motion

• elliptical orbits
• concentric circles
• epicycles
• linear motion

Copernicus proposed the _________ model of the universe

• static
• geocentric
• elliptical
• heliocentric

Geocentrism places _________ at the center of the universe

• Mars
• Jupiter
• The Sun
• Earth

Heliocentrism places ________ at the center of the universe

• the Earth
• the Sun
• the Moon
• Mars

The distance from the Earth to the Sun is

• 100 thousand miles

• 150 thousand kilometers
• 1 million kilometer

• 150 million kilometers

The angle at which we measure a stars distance from our planet is called

• ecliptic angle
• zenith angle
• declination angle
• parallax angle

The heliocentric model has been adopted because the ____ fits better with our observations

• Newtonian physics
• data

• quantum mechanics
• geocentric model