AST1002 Final Exam With
Complete Solution
Approximately how often do solar or lunar eclipses occur? - ANSWER Twice a
year
As the moon becomes more fully illuminated from one night to the next, it is
said to be - ANSWER waxing
The Moon's orbit around the Earth is elliptical, rather than circular. When do
you expect annular eclipses to occur? - ANSWER When it is farthest from us.
Which of the following phases of the Moon would NOT be observable at
midnight? - ANSWER waning crescent
If a star has a parallax of .25" of arc, then its distance from us must be: -
ANSWER 4 parsecs
If a star is viewed in a zodiacal constellation, then its observed parallax will
be: - ANSWER linear
If a star is viewed perpendicular to the ecliptic, its parallax motion will appear
to be: - ANSWER circular
Star A has a parallax angle which is twice as large as the parallax angle for
star B. How do their distances compare? - ANSWER Star B is twice as far away
from us as star A.
The planets with orbits closer to the Sun are moving faster. - ANSWER True
According to Kepler's laws of planetary motion, and confirmed by Newton's
,laws of motion and gravitation, this is true.
The geocentric model of Ptolemy was based on epicycles and deferents. -
ANSWER True
These were always taken to be circular.
If you double the distance between two objects, their mutual gravitational
attraction will be halved. - ANSWER False
The mutual gravitational force would be one-fourth as great if the distance is
doubled
Earth is held in orbit around the Sun by centrifugal force. - ANSWER False
Rather than a center-fleeing (centrifugal) force, Earth experiences a
center-seeking (centripetal) acceleration due to the gravitational attraction
between it and the Sun
The Ptolemaic and Copernican models provide differing predictions of the
phases of Venus. - ANSWER True
The "full" phase of Venus would not be seen in the Ptolemaic model.
The orbital period of an object is independent of the mass of its parent body.
- ANSWER False
See the modified form of Kepler's third law
If our Sun were twice as massive as it is now but the solar system were
otherwise identically populated and arranged, it would take 730.5 days for
Earth to complete one orbit of the Sun. - ANSWER False
The denominator of the modified form of Kepler's third law in Section 1.4
would be 2 solar masses. The period would thus be shorter by a factor of the
,square root of 2, or about 365.256/1.414 = 258 days, if the Sun were twice as
massive.
Both the heliocentric theory and the geocentric theory of the solar system
were able to model and predict retrograde motion of the planets. - ANSWER
True
The retrograde loops of Mars, Jupiter, and Saturn, as well as the
back-and-forth motion of Mercury and Venus and the motion of the Moon,
were well known to ancient astronomers and were the reason Ptolemy
included epicycles in his geocentric model.
Kepler's third law states that period is independent of the size of a planet's
orbit. - ANSWER False
You realized that the dependence of period on distance was one of the basic
properties of orbits from Kepler's three laws.
Gravity acts on an object only when it is close to the surface of the Earth. -
ANSWER False
Newton agreed with Aristotle that the natural state of an object was to be at
rest and that objects will return to rest if all external forces are removed. -
ANSWER False
The eccentricity e gives us the size of an ellipse. - ANSWER False
The eccentricity only tells us the degree to which the ellipse is flattened with
respect to a perfect circle
The Sun is not located at the center of an elliptical orbit, but is offset
somewhat toward one of its ends. - ANSWER True
, The Sun actually occupies one focus of the ellipse, and the other focus is
empty
The Greek philosopher Claudius Ptolemaeus (Ptolemy) taught that all
heavenly bodies moved in perfect circular orbits centered on the Earth. -
ANSWER False
Perfect circular orbits centered on the Earth do not explain the retrograde
motion of the planets. To explain this, Ptolemy introduced epicycles and
deferents
The Greek philosopher Aristotle taught that all heavenly bodies moved in
perfect circular orbits centered on the Earth. - ANSWER True
Aristotle's ideas did not include the complications of epicycles and deferents
that were needed to explain variations in planet brightness and retrograde
motion, nor did they explain the back-and-forth motion of Venus and
Mercury compared to the Sun.
One of the biggest challenges for early astronomers was explaining the
motion of the planets. - ANSWER True
While the motions of the Moon and the Sun in the sky are fairly simple and
predictable, the planets seem to move in a much more complex way,
sometimes even seeming to stop and move in the reverse direction.
The value for the astronomical unit (AU) is determined by measuring the
distance from the Earth to Venus using radar. - ANSWER True
Since Kepler had worked out the distance to Venus in terms of the
astronomical unit, it is possible to determine the value of the astronomical
unit when the distance from the Earth to Venus is determined.
Complete Solution
Approximately how often do solar or lunar eclipses occur? - ANSWER Twice a
year
As the moon becomes more fully illuminated from one night to the next, it is
said to be - ANSWER waxing
The Moon's orbit around the Earth is elliptical, rather than circular. When do
you expect annular eclipses to occur? - ANSWER When it is farthest from us.
Which of the following phases of the Moon would NOT be observable at
midnight? - ANSWER waning crescent
If a star has a parallax of .25" of arc, then its distance from us must be: -
ANSWER 4 parsecs
If a star is viewed in a zodiacal constellation, then its observed parallax will
be: - ANSWER linear
If a star is viewed perpendicular to the ecliptic, its parallax motion will appear
to be: - ANSWER circular
Star A has a parallax angle which is twice as large as the parallax angle for
star B. How do their distances compare? - ANSWER Star B is twice as far away
from us as star A.
The planets with orbits closer to the Sun are moving faster. - ANSWER True
According to Kepler's laws of planetary motion, and confirmed by Newton's
,laws of motion and gravitation, this is true.
The geocentric model of Ptolemy was based on epicycles and deferents. -
ANSWER True
These were always taken to be circular.
If you double the distance between two objects, their mutual gravitational
attraction will be halved. - ANSWER False
The mutual gravitational force would be one-fourth as great if the distance is
doubled
Earth is held in orbit around the Sun by centrifugal force. - ANSWER False
Rather than a center-fleeing (centrifugal) force, Earth experiences a
center-seeking (centripetal) acceleration due to the gravitational attraction
between it and the Sun
The Ptolemaic and Copernican models provide differing predictions of the
phases of Venus. - ANSWER True
The "full" phase of Venus would not be seen in the Ptolemaic model.
The orbital period of an object is independent of the mass of its parent body.
- ANSWER False
See the modified form of Kepler's third law
If our Sun were twice as massive as it is now but the solar system were
otherwise identically populated and arranged, it would take 730.5 days for
Earth to complete one orbit of the Sun. - ANSWER False
The denominator of the modified form of Kepler's third law in Section 1.4
would be 2 solar masses. The period would thus be shorter by a factor of the
,square root of 2, or about 365.256/1.414 = 258 days, if the Sun were twice as
massive.
Both the heliocentric theory and the geocentric theory of the solar system
were able to model and predict retrograde motion of the planets. - ANSWER
True
The retrograde loops of Mars, Jupiter, and Saturn, as well as the
back-and-forth motion of Mercury and Venus and the motion of the Moon,
were well known to ancient astronomers and were the reason Ptolemy
included epicycles in his geocentric model.
Kepler's third law states that period is independent of the size of a planet's
orbit. - ANSWER False
You realized that the dependence of period on distance was one of the basic
properties of orbits from Kepler's three laws.
Gravity acts on an object only when it is close to the surface of the Earth. -
ANSWER False
Newton agreed with Aristotle that the natural state of an object was to be at
rest and that objects will return to rest if all external forces are removed. -
ANSWER False
The eccentricity e gives us the size of an ellipse. - ANSWER False
The eccentricity only tells us the degree to which the ellipse is flattened with
respect to a perfect circle
The Sun is not located at the center of an elliptical orbit, but is offset
somewhat toward one of its ends. - ANSWER True
, The Sun actually occupies one focus of the ellipse, and the other focus is
empty
The Greek philosopher Claudius Ptolemaeus (Ptolemy) taught that all
heavenly bodies moved in perfect circular orbits centered on the Earth. -
ANSWER False
Perfect circular orbits centered on the Earth do not explain the retrograde
motion of the planets. To explain this, Ptolemy introduced epicycles and
deferents
The Greek philosopher Aristotle taught that all heavenly bodies moved in
perfect circular orbits centered on the Earth. - ANSWER True
Aristotle's ideas did not include the complications of epicycles and deferents
that were needed to explain variations in planet brightness and retrograde
motion, nor did they explain the back-and-forth motion of Venus and
Mercury compared to the Sun.
One of the biggest challenges for early astronomers was explaining the
motion of the planets. - ANSWER True
While the motions of the Moon and the Sun in the sky are fairly simple and
predictable, the planets seem to move in a much more complex way,
sometimes even seeming to stop and move in the reverse direction.
The value for the astronomical unit (AU) is determined by measuring the
distance from the Earth to Venus using radar. - ANSWER True
Since Kepler had worked out the distance to Venus in terms of the
astronomical unit, it is possible to determine the value of the astronomical
unit when the distance from the Earth to Venus is determined.
