Astronomy: The Modern View

Mars, Jupiter, and Saturn show retrograde motion because

• planets move on epicycles. 
• planets orbit the Sun in the same direction.
• Earth moves faster in its orbit. 
• they rotate quickly on their axes.

How did the geocentric model account for day and night on Earth?

• The Earth rotated
• The Sun orbited Earth
• The geocentric model couldn't account for day and night
• The Earth revolved around the Sun

Epicycles were used in Ptolemy’s model to explain

• why planets moved in the sky.
• why Earth was at the center. 
• why retrograde motion occurred.
• why inner planets were always seen near the Sun.

The geocentric model was supported by Aristotle because

• we don't feel as though Earth moves
• objects fall toward Earth, not the Sun
• we don't see an enormous wind
• all of these were valid reasons

The heliocentric model assumes

• planets move on epicycles
• Earth is the center of the solar system
• the stars move on the celestial sphere
• the Sun is the center of the solar system

Copernicus' important contribution to astronomy was

• proving planets move around the Sun in elliptical orbits
• the theory of gravity
• proposing a simpler model for the motions of planets in the solar system
• discovering the Sun was not at the center of the Milky Way

Copernicus' heliocentric model was flawed because...

• he assumed planets moved in ellipses.
• he didn't know about Uranus and Neptune.
• he couldn't explain retrograde motion.
• he assumed planets moved in circles.

Who published the first astronomical observations made with a telescope?

• Copernicus
• Galileo
• Brahe
• Kepler

Which of Galileo's initial observations was most challenging to established geocentric beliefs?

• craters on the Moon
• sunspots
• lunar maria
• satellites of Jupiter?

Which hero of the Renaissance postulated three "laws" of planetary motion?

• Kepler
• Newton
• Galileo
• Copernicus