ASTRO 101 EXAM 2
Based on the video, which Venus phase would be impossible to see (from Earth)
if Venus orbited Earth as described in Ptolemy's Earth-centered model?
gibbous (nearly full)
Phases that show more than a crescent are not possible in Ptolemy's Earth-
centered model, so a gibbous or full Venus could never occur if Venus orbited
Earth.
Which of the following can you observe about Venus with the naked eye? Select
all that apply.
Venus sometimes shines brightly in the eastern sky shortly before dawn
Venus sometimes shines brightly in the western sky shortly after sunset
(Venus always remains close to the Sun in our sky. Therefore, when it is visible, it
is either in the evening sky for up to a few hours after sunset or in the morning sky
for up to a few hours before dawn.)
In Ptolemy's Earth-centered model, when would Venus appear directly behind
the Sun as viewed from Earth?
never
(In the Earth-centered model, Venus always remains somewhere between Earth
and the Sun, and never appears behind the Sun in our sky)
,As you learned in the video, Galileo's observations of Venus in gibbous (nearly
full) phase showed conclusively that Venus orbits the Sun, not Earth. Which
figure shows Venus's position when Galileo saw it in gibbous phase?
Notice that the gibbous phase occurs when Venus is farther from Earth than the
Sun, and this could never happen in Ptolemy's system. That is how Galileo
concluded that Venus must orbit the Sun.
In the Greek geocentric model, the retrograde motion of a planet occurs when:
The planet actually goes backward in its orbit around Earth.
Consider the hypothetical observation "a planet beyond Saturn rises in west,
sets in east." This observation is not consistent with a Sun-centered model,
because in this model
The rise and set of all objects depends only on Earth's rotation
(Earth rotates from west to east, so objects in the sky must appear to go across
our sky from east to west)
We never see a crescent Jupiter from Earth because Jupiter __________
is farther than Earth from the Sun.
(An object must come between Earth and the Sun for us to see it in a crescent
phase, which is why we see crescents only for Mercury, Venus, and the Moon.)
, Which of the following was not a major advantage of Copernicus's Sun-centered
model over the Ptolemaic model?
It made significantly better predictions of planetary positions in our sky.
Galileo's contribution to astronomy included
making observations and conducting experiments that dispelled scientific
objections to the Sun-centered model.
In Ptolemy's Earth-centered model for the solar system, Venus's phase is never
full as viewed from Earth because it always lies between Earth and the Sun. In
reality, as Galileo first recognized, Venus is __________.
full whenever it is on the opposite side of the Sun from Earth
(A full Venus always occurs when it is on the opposite side of the Sun as viewed
from Earth. Galileo used this fact as evidence for the Sun-centered view of the
solar system: The fact that Venus goes through all the phases must mean it goes
all the way around the Sun. In contrast, in the Ptolemaic model, Venus only varies
between new and crescent phases.)
Imagine that Venus is in its full phase today. If we could see it, at what time
would the full Venus be highest in the sky?
at noon
Based on the video, which Venus phase would be impossible to see (from Earth)
if Venus orbited Earth as described in Ptolemy's Earth-centered model?
gibbous (nearly full)
Phases that show more than a crescent are not possible in Ptolemy's Earth-
centered model, so a gibbous or full Venus could never occur if Venus orbited
Earth.
Which of the following can you observe about Venus with the naked eye? Select
all that apply.
Venus sometimes shines brightly in the eastern sky shortly before dawn
Venus sometimes shines brightly in the western sky shortly after sunset
(Venus always remains close to the Sun in our sky. Therefore, when it is visible, it
is either in the evening sky for up to a few hours after sunset or in the morning sky
for up to a few hours before dawn.)
In Ptolemy's Earth-centered model, when would Venus appear directly behind
the Sun as viewed from Earth?
never
(In the Earth-centered model, Venus always remains somewhere between Earth
and the Sun, and never appears behind the Sun in our sky)
,As you learned in the video, Galileo's observations of Venus in gibbous (nearly
full) phase showed conclusively that Venus orbits the Sun, not Earth. Which
figure shows Venus's position when Galileo saw it in gibbous phase?
Notice that the gibbous phase occurs when Venus is farther from Earth than the
Sun, and this could never happen in Ptolemy's system. That is how Galileo
concluded that Venus must orbit the Sun.
In the Greek geocentric model, the retrograde motion of a planet occurs when:
The planet actually goes backward in its orbit around Earth.
Consider the hypothetical observation "a planet beyond Saturn rises in west,
sets in east." This observation is not consistent with a Sun-centered model,
because in this model
The rise and set of all objects depends only on Earth's rotation
(Earth rotates from west to east, so objects in the sky must appear to go across
our sky from east to west)
We never see a crescent Jupiter from Earth because Jupiter __________
is farther than Earth from the Sun.
(An object must come between Earth and the Sun for us to see it in a crescent
phase, which is why we see crescents only for Mercury, Venus, and the Moon.)
, Which of the following was not a major advantage of Copernicus's Sun-centered
model over the Ptolemaic model?
It made significantly better predictions of planetary positions in our sky.
Galileo's contribution to astronomy included
making observations and conducting experiments that dispelled scientific
objections to the Sun-centered model.
In Ptolemy's Earth-centered model for the solar system, Venus's phase is never
full as viewed from Earth because it always lies between Earth and the Sun. In
reality, as Galileo first recognized, Venus is __________.
full whenever it is on the opposite side of the Sun from Earth
(A full Venus always occurs when it is on the opposite side of the Sun as viewed
from Earth. Galileo used this fact as evidence for the Sun-centered view of the
solar system: The fact that Venus goes through all the phases must mean it goes
all the way around the Sun. In contrast, in the Ptolemaic model, Venus only varies
between new and crescent phases.)
Imagine that Venus is in its full phase today. If we could see it, at what time
would the full Venus be highest in the sky?
at noon
