solutions correct and complete
Astro 101 - Exam 1 UMich 199 all
solutions correct and complete
what is our planet in the solar system - ANSWER part of the solar system, in the milky way galaxy, in
local group of galaxies, in local supercluster
how did we come to be - ANSWER the Big Bang which produced hydrogen and helium
where did elements come from - ANSWER 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 - ANSWER human civilization is a second of a year, and
our own life is a fraction of a second
how is earth moving - ANSWER 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 - ANSWER altitude above the horizon and
direction along the horizon
why do stars rise and set - ANSWER because of Earth's rotation
why do the constellations we see depend on latitude and time of year - ANSWER your location
determines which constellations are hidden by earth
the time of year determines the location of the Sun and the celestial sphere
what causes the seasons - ANSWER the tilt of the Earth's axis
,Astro 101 - Exam 1 UMich 199 all
solutions correct and complete
what are the summer and winter solstices - ANSWER when the Northern hemisphere gets its most and
least direction sunlight
what are the spring and fall equinoxes - ANSWER when both hemispheres get direct and equal sunlight
how does the orientation of Earth's axis change with time - ANSWER 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 - ANSWER 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 - ANSWER -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 - ANSWER 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 - ANSWER The Ptolemaic model had each planet move on
a small circle whose center moves around Earth on a larger circle
Copernicus - ANSWER created a Sun-centered model
Tycho - ANSWER provided the data needed to improve Copernicus' model
Kepler - ANSWER found a model that fit Tycho's data
, Astro 101 - Exam 1 UMich 199 all
solutions correct and complete
Kepler's 1st Law of Planetary Motion - ANSWER each planet orbits the sun in a path called an ellipse with
the sun at one focus
Kepler's Second Law of Planetary Motion - ANSWER 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 - ANSWER 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 - ANSWER his experiments and observations overcame the remaining objections to the Sun-
centered solar system model
what is a scientific theory - ANSWER A model that explains a wide variety of observations in terms of a
few general principles and that has survived repeated and varied testing
how is astrology different from astronomy - ANSWER - Astronomy is the scientific study of the universe
and the celestial objects within it
- Astrology assumes that the positions of celestial
objects influence human events
speed - ANSWER distance/time
rate at which objects move