# Astronomy – Ch. 0 – Ch. 3

(T/F) The Milky Way Galaxy is about 1 million times larger than Earth.
False
(T/F) The stars in a constellation are physically close to one another.
False
(T/F) The solar day is longer than the sidereal day.
True
(T/F) The seasons are caused by the precession of Earth’s axis.
False
(T/F) A lunar eclipse can occur only during the full phase.
True
(T/F) The angular diameter of an object is inversely proportional to its distance from the observer.
True
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(T/F) If we know the distance of an object from Earth, we can determine the object’s size by measuring its parallax.
False
If Earth rotated twice as fast as it currently does, but its motion around the sun stayed the same, then
a. the night would be twice as long
b. the night would be half as long
c. the year would be half as long
d. the length of the day would be unchanged
B. the night would be half as long
A long, thin cloud that stretched from directly overhead to the western horizon would have an angular size of
a. 45 degrees
b. 90 degrees
c. 180 degrees
d. 360 degrees
B. 90 degrees
When a thin crescent of the moon is visible just before sunrise, the moon is in its
a. waxing phase
b. new phase
c. waning phase
d. quarter phase
c. waning phase
If the moon orbit were a little larger, solar eclipses would be
a. more likely to be annular
b. more likely to be total
c. more frequent
d. unchanged in appearance
a. more likely to be annular
If the moon orbited Earth twice as fast, but in the same orbit, the frequency of the solar eclipses would
a. double
b. be cut in half
c. stay the same
c. stay the same
According to Figure 0.8, the Zodiac, in January the sun is in the constellation
a. Cancer
b. Gemini
c. Leo
d. Aquarius
d. Aquarius
In Figure 0.19, (Triangulation), using a longer baseline would result in
a. a less accurate distance to the tree
b. a more accurate distance to the tree
c. a smaller angle at point b
d. a greater distance across the river
b. a more accurate distance to the tree
In Figure 0.20, (Parallax), a smaller Earth would result in
a. a smaller parallax angle
b. a shorter distance measured to the object
c. a larger apparent displacement
d. stars appearing closer together
a. a smaller parallax
What is the path that the Sun, Moon, and planets follow through the constellations?
a) the celestial equator
b) the north celestial pole
c) the Milky Way
d) the zodiac
e) the ecliptic
e. the ecliptic
What causes Earth’s seasons?
a) Wobble of Earth’s rotation axis
b) the greenhouse effect
c) 23.5° tilt of Earth’s rotational axis
d) movement of Earth closer to or farther from
the Sun
e) global warming and cooling
c. the 23.5 degrees tilt of Earth’s rotational axis
A total lunar eclipse occurs
a) during the new moon phase.
b) when the Sun blocks the Moon.
c) during the full moon phase.
d) always around the summer solstice
c. during the full moon phase
Constellations (and the moon) appear to move across the sky at night because
a) the Earth orbits the Sun.
b) the Moon orbits the Earth.
c) stars are in constant motion.
d) the Sun orbits the Earth.
e) the Earth spins on its axis.
e. the Earth spins on its axis
(T/F) Aristotle proposed that all planets revolve around the Sun.
False
(T/F) During retrograde motion, planets actually stop and move backward in space.
False
(T/F) The heliocentric model holds that the Earth is at the center and everything else moves around it.
False
(T/F) Copernicus’s theories gained widespread scientific acceptance during his life time.
False
(T/F) Galileo’s observations of the sky were made with the naked eye.
False
(T/F) The speed of a planet orbiting the Sun is independent of the planet’s position in its orbit.
False
(T/F) Kepler’s laws hold only for the six planet known in his time.
False
(T/F) You throw a baseball to someone; before the ball is caught, it is temporarily in orbit around Earth’s center.
True
A major flaw in Copernicus’s model was that it still had
a. the Sun at the center
b. Earth at the center
d. circular orbits
d. circular orbits
An accurate sketch of Mar’s orbit around the Sun would show
a. the Sun far off center
b. an oval twice as long as it is wide
c. a nearly perfect circle
d. phases
c. a nearly perfect circle
A calculation of how long it takes a planet to orbit the Sun would be most closely related to Kepler’s
a. first law of orbital shapes
b. second law of orbital speeds
c. third law of planetary distances
d. first law of inertia
c. third law of planetary distances
An asteroid with an orbit lying entirely inside Earth’s
a. has an orbital semimajor axis of less than 1 AU
b. has a longer orbital period than Earth’s
c. moves more slowly than Earth
d. has a highly eccentric orbit
a. has an orbital semimajor axis of less than 1 AU
If Earth’s orbit around the Sun were to double in size, the new “year” would be
a. less than 2
b. 2
c. more than 2
d. more than 2 current Earth years
c. more than 2
As shown in Figure 1.8 (Venus Phases), Galileo’s observations demonstrated that Venus must be
a. orbiting Earth
b. orbiting the Sun
c. larger than Earth
d. similar to the Moon
b. orbiting the Sun
Figure 1.17, showing the motion of a ball near Earth’s surface, depicts how gravity
a. causes the ball to accelerate downward.
b. has no effect on the ball.
c. increases with altitude.
d. causes the ball to accelerate upward.
a. causes the ball to accelerate downward.
How long (s) would a radar signal take to complete the round-trip between Earth and Mars when the planets are 1.1 AU apart?
1100 s
Review scientific notation.
Copernicus’ important contribution to astronomy was
a) proving planets move around the Sun in elliptical orbits.
b) the theory of gravity.
c) proposing a model that easily explained the retrograde motions of the planets.
d) discovering the Sun was not at the center of the Milky Way.
e) discovering the four moons of Jupiter.
c) proposing a model that easily explained the retrograde motions of the planets.
Who published the first astronomical observations made with a telescope?
a) Hipparchus
b) Galileo
c) Aristotle
d) Copernicus
e) Kepler
b. Galileo
Earth is closer to the Sun in January. From this fact, Kepler’s 2nd law tells us
a) Earth orbits slower in January.
b) Earth orbits faster in January.
c) Earth’s orbital speed doesn’t change.
b. Earth orbits faster in January.
How did the geocentric model account for day and night on Earth?
a) The Earth rotated.
b) The Sun rotated.
c) The geocentric model couldn’t account for day and night.
d) The Earth revolved around the Sun.
e) The Sun orbited Earth.
e. the Sun orbited Earth
Considering the Moon’s phases, everyone on Earth sees
a) the same phase in 24 hours.
b) different phases in 24 hours.
c) a lunar eclipse once a month.
d) different sides of the Moon.
a. the same phase in 24 hours.
(T/F) Imagine an emission spectrum produced by a container of hydrogen gas. Changing the amount of hydrogen in the container will change the colors of the lines in the spectrum.
False
Imagine an emission spectrum produced by a container of hydrogen gas. Changing the gas in the container from hydrogen to helium will change the colors of the lines in the spectrum.
True
Two otherwise identical objects have temperatures of 1000 K and 1200 K respectively. The object at 1200 K emits roughly twice as much radiation as the object at 1000 K.
True
An electron moves to a higher energy level in an atom after absorbing a photon of a specific energy.
True
As you drive away from a radio transmitter, the radio signal you receive from the station is shifted to longer wavelengths.
True
The wavelength of green light is about the size of an atom.
False
The energy of a photon is inversely proportional to the wavelength of the radiation.
True
a. wavelength
b. amplitude
c. frequency
d. energy
a. wavelength
An X-ray telescope located in Antarctica would not work well because of
a. the extreme cold
b. the ozone hole
c. continuous daylight
d. Earth’s atmosphere
d. Earth’s atmosphere
A star much cooler than the Sun would appear
a. red
b. blue
c. smaller
d. larger
a. red
The blackbody curve of a star moving toward Earth would have its peak shifted
a. to lower intensity
b. toward higher energies
c. toward longer wavelengths
d. toward lower energies
b. toward higher energies
The visible spectrum of sunlight reflected from Saturn’s cold moon Titan would be expected to be
a. continuous
b. an emission spectrum
c. an absorption spectrum
c. an absorption spectrum
Astronomers analyze starlight to determine a star’s
a. temperature
b. composition
c. motion
d. all of the above
d. all of the above
According to Figure 2.11 (Blackbody Curves), an object having a temperature of 1000 K emits mostly
a. infrared light
b. visible light
c. ultraviolet light
d. X-rays
a. infrared light
In Figure 2.20 (Atomic Excitation), the total energy of the two photons emitted in the branch at the lower right is
a. greater than
b. less than
c. approximately equal to
d. exactly equal to
the energy of the UV photon absorbed at the left
d. exactly equal to
Newton’s law of gravity states that the force between two objects
a) increases with distance.
b) depends on the state of matter (solid, liquid, or gas).
c) can be attractive or repulsive.
d) increases with mass.
d. increases with mass
Gravity is
a) sometimes a repulsive force and sometimes an attractive force.
b) always a repulsive force.
c) always an attractive force.
d) none of the above.
c. always an attractive force
The distance between successive wave crests defines the ________ of a wave.
a) wavelength
b) frequency
c) period
d) amplitude
e) energy
a. wavelength
Which of these is NOT a form of electromagnetic radiation?
a) gamma rays
b) infrared
c) sound
d) visible light
c. sound
At a football game, the “wave” might circulate through the stands and move around the stadium. In this wave motion, people stand up and sit down as the wave passes. What type of wave would this be characterized as?
a) polarized wave
b) longitudinal wave
c) lateral wave
d) transverse wave
e) soliton wave
d. transverse wave
What types of electro-magnetic radiation from space reach the surface of Earth?
b) X rays & ultraviolet light
c) infrared & gamma rays
d) visible light & radio waves
e) visible & ultraviolet light
d. visible light and radio waves
Rigel appears as a bright bluish star, whereas
Betelgeuse appears as a bright reddish star.
Rigel is ______ Betelgeuse.
a) cooler than
b) the same temperature as
c) older than
d) hotter than
e) more massive than
d. hotter than
You are gradually heating a lump of rock in an oven to extremely high temperatures.
As it heats up, the lump emits nearly perfect theoretical blackbody radiation, meaning
that it
a) is brightest when hottest.
b) is bluer when hotter.
c) is both (a) and (b).
d) is neither.
c. is both a and b
The wavelengths of emission lines produced by an element
a) depend on its temperature.
b) are identical to its absorption lines.
c) depend on its density.
d) are different than its absorption lines.
e) depend on its intensity.
b. are identical to its absorption lines
The main advantage to using the HST is the increased amount of “nighttime” viewing it affords.
False
The term “seeing” is used to describe how faint an object can be detected by a telescope.
False
One of the primary advantages of CCDs over photographic plates is the former’s high efficiency in detecting light.
True
Radio telescopes are large in part to improve their angular resolution, which is poor because of the long wavelengths at which they are used to observe the skies.
True
Infrared astronomy can only be done from space.
False
Gamma-ray telescopes employ the same basic design that optical instruments use.
False
Because gamma rays have very short wavelengths, gamma-ray telescopes can achieve extremely high angular resolution.
False
The main reason that most professional research telescopes are reflectors is that
a. mirror produce sharper images than lenses do
b. their images are inverted
c. they do not suffer from the effects of seeing
d. large mirrors are easier to build than large lenses
d. large mirrors are easier to build than large lenses
If telescope mirrors could be made in odd sizes, the one with the most light-gathering power would be
a. a triangle with 1-m sides
b. a square with 1-m sides
c. a circle 1 m in diameter
d. a rectangle with two 1-m sides and two 2-m sides
d. a rectangle with two 1-m and two 2-m sides
The primary reason professional observatories are built on the highest mountaintops is to
a. get away from city lights
b. be above rain clouds
c. reduce atmospheric blurring
d. improve chromatic aberration
c. reduce atmosphere blurring
When multiple radio telescopes are used for interferometry, resolving power is most improved by increasing
a. the distance between telescopes
b. the number of telescopes in a given area
c. the diameter of each telescope
d. the electrical power supplied to each telescope.
a. the distance between telescopes
The Spitzer Space Telescope is stationed far from Earth because
a. this increases the telescope’s field of view
b. the telescope is sensitive to electromagnetic interference form terrestrial radio stations
c. doing so avoids the obscuring effects of Earth’s atmosphere
d. Earth is a heat source and the telescope must be kept very cool
d. Earth is a heat source and the telescope must be kept very cool
The best way to study young stars hidden behind interstellar dust clouds would be to use
a. X-rays
b. infrared light
c. ultraviolet light
d. blue light
b. infrared light
The image shown in Figure 3.12 (Resolution) is sharpest when the ratio of wavelength to telescope size is
a. larger
b. small
c. close to one
d. none of these
b. small
Table 3.1 (Astronomy at Many Wavelengths) suggests that the best frequency range in which to study the hot (million-kelvin) gas found among the galaxies in the Virgo cluster would be
b. in the infrared
c. in X-rays
d. in gamma rays
c. in X-rays
If a light source is approaching you, you will observe
a) its spectral lines are redshifted.
b) the light is much brighter.
c) its spectral lines are shorter in wavelength.
d) the amplitude of its waves has increased.
e) its photons have increased in speed.
c. its spectral lines are shorter in wavelength
An advantage of CCDs over photographic film is
a) they don’t require chemical development.
b) digital data is easily stored & transmitted.
c) CCDs are more light sensitive than film.
d) CCD images can be developed faster.
e) All of the above are true.
e. all of the above
The Hubble Space Telescope (HST) offers sharper images than ground telescopes
primarily because
a) HST is closer to planets & stars.
b) HST uses a larger primary mirror.
c) it gathers X-ray light.
d) HST orbits above the atmosphere.
e) it stays on the nighttime side of Earth.
d. HST orbits above the atmosphere
When light hits a barrier edge, what happen to the light that passes by?
Light bends around the barrier; diffraction
Diffraction is the tendency of light to
a) bend around corners and edges.
b) separate into its component colors.
c) bend through a lens.
d) disperse within a prism.
e) reflect off a mirror.
a. bend around corners and edges
a) observations can be made day & night.
b) we can see objects that don’t emit visible light.
c) radio waves are not blocked by interstellar dust.
d) they can be linked to form interferometers.
e) All of the above are true.
e. all of the above
Infrared telescopes are very useful for observing
a) pulsars & black holes.
b) from locations on the ground.
c) hot stars & intergalactic gas.
d) neutron stars.
e) cool stars & star-forming regions
e. cool stars and star forming regions
What is the wavelength of a 110-MHz radio signal?
2.7273 m