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Astro 101 - Exam 1 UMich Questions and
Correct Answers
what is our planet in the solar system Ans: part of the solar
system, in the milky way galaxy, in local group of galaxies, in local
supercluster
how did we come to be Ans: the Big Bang which produced
hydrogen and helium
where did elements come from Ans: the big bang produced H and
He, which are the base of other elements constructed in stars
how old are we in comparison to the universe Ans: human
civilization is a second of a year, and our own life is a fraction of a
second
how is earth moving Ans: earth rotates on an axis once a day and
orbits the Sun at 1 AU (150 million kilometers)
how can we specify the position of an object in the local sky Ans:
altitude above the horizon and direction along the horizon
why do stars rise and set Ans: because of Earth's rotation
why do the constellations we see depend on latitude and time of
year Ans: your location determines which constellations are
hidden by earth
the time of year determines the location of the Sun and the
celestial sphere
© 2025 All rights reserved
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what causes the seasons Ans: the tilt of the Earth's axis
what are the summer and winter solstices Ans: when the Northern
hemisphere gets its most and least direction sunlight
what are the spring and fall equinoxes Ans: when both
hemispheres get direct and equal sunlight
how does the orientation of Earth's axis change with time Ans: the
tilt remains about 23.5 degrees (so the season pattern is not
affected) but the the cycle slowly and subtly changes the
orientation of earth's axis every 26,000 years
why do we see phases of the moon Ans: half the Moon is lit by the
Sun, half is in shadow, and its appearance to us is determined by
the relative positions of the Sun, Moon, and Earth
what causes eclipses Ans: -Lunar eclipse: Earth's shadow on the
Moon
-Solar eclipse: Moon's shadow on Earth
-Tilt of Moon's orbit means eclipses occur during two periods each
year
what was mysterious about the planetary motion in our sky Ans:
like the sun and moon, planets usually drift eastward relative to
the stars from night to night, but sometimes, for a few weeks or
few months, a planet turns westward in its apparent retrograde
motion
how did the Greeks explain planetary motion Ans: The Ptolemaic
model had each planet move on a small circle whose center moves
around Earth on a larger circle
© 2025 All rights reserved
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Copernicus Ans: created a Sun-centered model
Tycho Ans: provided the data needed to improve Copernicus'
model
Kepler Ans: found a model that fit Tycho's data
Kepler's 1st Law of Planetary Motion Ans: each planet orbits the
sun in a path called an ellipse with the sun at one focus
Kepler's Second Law of Planetary Motion Ans: As a planet moves
around its orbit it sweeps out equal areas in equal times.
a planet travels faster when it is nearer to the sun and slower
when it is farther form the sun
Kepler's Third Law of Planetary Motion Ans: The square of the
orbital period of any satellite is proportional to the cube of its
average distance from its central mass
More distant planets orbit the Sun at slower average speeds: p2 =
a3 (p= orbital period in years and a= average distance from Sun in
AU)
Galileo Ans: his experiments and observations overcame the
remaining objections to the Sun-centered solar system model
what is a scientific theory Ans: A model that explains a wide
variety of observations in terms of a few general principles and
that has survived repeated and varied testing
© 2025 All rights reserved
Astro 101 - Exam 1 UMich Questions and
Correct Answers
what is our planet in the solar system Ans: part of the solar
system, in the milky way galaxy, in local group of galaxies, in local
supercluster
how did we come to be Ans: the Big Bang which produced
hydrogen and helium
where did elements come from Ans: the big bang produced H and
He, which are the base of other elements constructed in stars
how old are we in comparison to the universe Ans: human
civilization is a second of a year, and our own life is a fraction of a
second
how is earth moving Ans: earth rotates on an axis once a day and
orbits the Sun at 1 AU (150 million kilometers)
how can we specify the position of an object in the local sky Ans:
altitude above the horizon and direction along the horizon
why do stars rise and set Ans: because of Earth's rotation
why do the constellations we see depend on latitude and time of
year Ans: your location determines which constellations are
hidden by earth
the time of year determines the location of the Sun and the
celestial sphere
© 2025 All rights reserved
, 2 | Page
what causes the seasons Ans: the tilt of the Earth's axis
what are the summer and winter solstices Ans: when the Northern
hemisphere gets its most and least direction sunlight
what are the spring and fall equinoxes Ans: when both
hemispheres get direct and equal sunlight
how does the orientation of Earth's axis change with time Ans: the
tilt remains about 23.5 degrees (so the season pattern is not
affected) but the the cycle slowly and subtly changes the
orientation of earth's axis every 26,000 years
why do we see phases of the moon Ans: half the Moon is lit by the
Sun, half is in shadow, and its appearance to us is determined by
the relative positions of the Sun, Moon, and Earth
what causes eclipses Ans: -Lunar eclipse: Earth's shadow on the
Moon
-Solar eclipse: Moon's shadow on Earth
-Tilt of Moon's orbit means eclipses occur during two periods each
year
what was mysterious about the planetary motion in our sky Ans:
like the sun and moon, planets usually drift eastward relative to
the stars from night to night, but sometimes, for a few weeks or
few months, a planet turns westward in its apparent retrograde
motion
how did the Greeks explain planetary motion Ans: The Ptolemaic
model had each planet move on a small circle whose center moves
around Earth on a larger circle
© 2025 All rights reserved
, 3 | Page
Copernicus Ans: created a Sun-centered model
Tycho Ans: provided the data needed to improve Copernicus'
model
Kepler Ans: found a model that fit Tycho's data
Kepler's 1st Law of Planetary Motion Ans: each planet orbits the
sun in a path called an ellipse with the sun at one focus
Kepler's Second Law of Planetary Motion Ans: As a planet moves
around its orbit it sweeps out equal areas in equal times.
a planet travels faster when it is nearer to the sun and slower
when it is farther form the sun
Kepler's Third Law of Planetary Motion Ans: The square of the
orbital period of any satellite is proportional to the cube of its
average distance from its central mass
More distant planets orbit the Sun at slower average speeds: p2 =
a3 (p= orbital period in years and a= average distance from Sun in
AU)
Galileo Ans: his experiments and observations overcame the
remaining objections to the Sun-centered solar system model
what is a scientific theory Ans: A model that explains a wide
variety of observations in terms of a few general principles and
that has survived repeated and varied testing
© 2025 All rights reserved
