254 terms

BYU Astronomy 127 Final

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Relative to the stars, the moon moves __________ from one night to the next.
to the east
What is the range of values that the celestial coordinate declination can have?
-90 to +90 degrees
You are on a strange planet. You note that the stars do not rise and set, but circle around parallel to the horizon. Then you travel over the surface of the planet in a straight parallel line until you reach a place where you observe the stars rise and set perpendicular to the horizon. If the distance that you traveled between these two points is 6,500 miles, what is the circumference of the planet?
26,000 miles

You have moved on the surface of the planet from one of the poles to the equator. This is one quarter of the total circumference. Thus, the circumference of the planet is 26,000 miles.
An eclipse of the moon can only occur when the moon is at
full phase
The main reason for it being hotter in summer than in winter is
the Sun is higher in the sky in the summer.
Polaris is presently the pole star, but it will not always be the pole star because the actual celestial pole moves among the stars due to the ______________________ of the Earth.
precession
Antares
Scorpio
Capella
Auriga
Altair
Aquila
Deneb
Cygnus
Aldebaran
Taurus
Castor
Gemini
Rigel
Orion
Vega
Lyra
Sirius
Canis Major
Procyon
Canis Minor
The Zodiac is
the constellations through which the Sun appears to travel in one year.
The horns of the crescent moon always point
away from the Sun.
A man located on the equator of the Earth notes one day that the center of the Sun crosses his meridian precisely 23.5 degrees north of his zenith. Therefore, the date is most likely
June 21.
The nearby open cluster known as the Pleiades is located in the constellation
Taurus
What was the major contribution made by Nicolaus Copernicus to astronomy?
He said that the Earth is not the center of the Universe.
The path that the Sun follows through the stars on the celestial sphere is known as
the ecliptic
What major contribution to astronomy was made by Tycho Brahe?
He made extensive and detailed observations of the positions of the planets.
What was one of the major contributions made by Isaac Newton to astronomy?
He developed a theory of gravity that could explain orbital motion.
What is the range of values that the celestial coordinate right ascension can have?
0 to 24 hours
An eclipse of the Sun can only occur when the moon is at
new phase
Relative to the stars, a planet in retrograde motion moves __________ from one night to the next.
toward the west
The nearby open cluster known as the Hyades is located in the constellation
Taurus
We live at 40° north latitude in Provo. How often is the Sun directly overhead at noon in Provo?
Never.
What was the major contribution made to astronomy by Johannes Kepler?
He discovered that the planets move around the Sun in elliptical orbits.
Regulus
Leo
Spica
Virgo
Betelguese
Orion
Pollux
Gemini
What happens in our model of the atom when an emission line is formed?
An electron moves from a higher energy level to a lower one.
If a radiating object is moving away from you, what effect do you observe in the object's spectrum?
It appears red-shifted.
If a telescope with an objective focal length of 5-feet is used with an eyepiece of 1/2 inch focal length, the resulting magnification will be:
120x
Which of the following is a problem inherent to individual radio telescopes?
They have poor angular resolution.

Since radio signals have wavelengths that are many orders of magnitude longer than visible light that is seen through optical telescopes, it is clear that individual radio telescopes would have poor angular resolution.
What is the primary advantage of the Hubble Space Telescope over ground-based telescopes?
It is above the atmosphere.
Green light is of ______________ than yellow light.
higher frequency and shorter wavelength
At full moon the Earth would appear to an observer on the Moon to be at _____ phase.
new

Phases of the Earth as viewed from the Moon are just the opposite of the phases of the Moon that we view from the Earth. The correct answer is new earth at full moon.
Adaptive optics are used to correct what problem?
Effects of atmospheric turbulence
Which of the following defines density?
Mass divided by volume
A telescope of large aperture is better than one of small aperture because of
greater resolving power.
A body is heated until it appears red in color. It is then heated further until it appears bluish in color. The amount of red light it gives off ____________ as the body becomes blue.
increases
Which of the following are the Jovian planets?
Jupiter, Saturn, Uranus, and Neptune
Today the phase of the moon is closest to being
Last quarter
Which of the following are the Terrestrial planets?
Venus, Mars, Earth, and Mercury
What is the primary ingredient in the Earth's atmosphere?
Nitrogen
The series of lines in the spectrum of hydrogen known as the Balmer series are seen in the visible portion of the spectrum and are characterized by electron transitions up from or down to the level n =
2
The light we see from the visible surface of the Sun comes from which atmospheric layer?
photosphere
What natural barrier tries to prevent two protons from combining during fusion?
Electromagnetic repulsion
Asteroids associated with the Lagrange points in the orbit of Jupiter are called
Trojan asteroids.
A 5th magnitude star is ____ times brighter than a 15th magnitude star.
10,000

A difference of 5 magnitudes is a difference in brightness of a factor of 100. A difference of 10 magnitudes would then be a difference in brightness of a factor of 100 x 100 or 10,000.
The average rate of erosion on the Moon is far less than that on the Earth because:
the Moon lacks an atmosphere and free water.
If you view a typical star with a spectrograph, what type of spectrum are you likely to observe?
Absorption

A typical star can be thought of as a hot object seen through a cooler gas. The result will be an absorption spectrum.
The absolute magnitude of a star is defined to be the apparent magnitude that the star would have if it were at a standard distance of ___ parsec(s).
10
A parsec is defined as the distance to a star which has a parallax of ___ second(s) of arc.
1.0
Which of these is the greatest distance? One light year, one parsec, one million kilometers, one billion nanometers, one trillion decimeters
One parsec
What result does the Greenhouse Effect have on the surface environment of Venus?
It has raised the surface temperature by hundreds of degrees Celsius.
Venus has a feature named Aphrodite Terra. What is this feature?
A continental-sized plateau
A nearby star has a parallax of 0.5 arc second. What is its distance?
2 pc

If the parallax is equal to 0.5 arc seconds, the distance is 1/0.5 or 2 parsecs.
What is the average length of time from one time of sunspot maximum on the Sun until the next time of sunspot maximum?
11 years
The absolute magnitude of the Sun is about
+5
The apparent magnitude of the Sun is about
-27
Which two physical properties contribute to the observed absolute magnitude or luminosity of an object?
surface temperature and size

Temperature and size are the two physical properties that determine the luminosity of an object radiating like a blackbody.
All F-type stars have approximately the same
temperature

Stars of the same spectral type will have about the same temperature.
Name the natural effect that tries to prevent two protons from combining or fusing.
Electromagnetic repulsion
In Provo, I see Polaris (the north star) at about 40 degrees above the horizon. I get in my car and drive 5 degrees south in latitude. How high above the horizon will Polaris appear at this new location?
35 degrees above the horizon

The altitude of Polaris is equal to your latitude. If you drive 5 degrees south of Provo, the altitude of the north star will then be 35 degrees.
A nearby star has a parallax of 0.25 arc second. What is its distance?
4 pc

distance = 1/p" so: 1/0.25 = 4 parsec
The chief cause of the differences observed among the various types of stellar spectra is the difference in _____________ from star to star.
surface temperature
An 8th magnitude star is about ____ times brighter than a 10th magnitude star.
6 3/10

There is a two magnitude difference between the two stars. This is a 6 3/10 difference in the brightness of the two stars.
Stars of which of the following spectral types would have the coolest surface temperature? F8, K1, G8, K4, G2
K4

In the spectral temperature sequence, K stars are cooler than F or G stars and a K4 star is cooler than a K1 star.
Which of the following apparent magnitudes is the brightest? -1, 0, 1, 5, 10
-1

In the magnitude scale, the smallest or most negative number in a list represents the brightest object.
What is the most important physical characteristic in determining the time that a given star spends on the main sequence?
Mass
Which star has the longest main sequence life expectancy? A star of 1/ 2 solar mass, a star of 5 solar masses, a star of 10 solar masses, the Sun, a G-type star
A star of 1/ 2 solar mass

Lower mass stars live longer than stars with higher mass. A star of 1/2 solar mass is the least massive star on the list and will thus live the longest on the main sequence.
What inevitably forces a star like the Sun to evolve away from being a main sequence star?
It builds up a core of helium.
Stars which are just forming (protostars) radiate most of their energy and are most commonly detected in
infrared.
A 1st magnitude star is about _______ times brighter than a 7th magnitude star.
251

This is a difference of six magnitudes. The brightness difference is then 2.51 x 100 or a factor of 251.
The spectrum of a typical gaseous nebula illuminated by a B-type star is
an emission spectrum.
Which two ingredients are needed to make an emission nebula?
Hot stars and interstellar gas
A mass of material is condensing into a star. If this "protostar" contains one half the mass of the Sun, when it finally contracts to the main sequence stage it will most likely be of spectral type
K

If the protostar is less massive than the Sun, the final main sequence star will also be less massive and therefore cooler and less luminous than the Sun. The only choice from the list is spectral type K.
What effect does interstellar dust have on visible light passing through it?
It dims and reddens it.
The type of intrinsic variable stars known as ___________ stars have periods ranging from a few hours to one day and are often found in globular clusters, and for that reason they are sometimes referred to as cluster variables. They are often used to estimate distances to globular clusters.
RR Lyrae
A galactic cluster is young if
it has an H-R diagram that resembles a complete main sequence.
The masses of stars other than the Sun would be unknown without the study of:
binary stars.
Which of the following definitely does not agree with present theories of stellar evolution? Some stars may remain on the main sequence for billions of years, a possible end phase of stellar evolution is the white dwarf stage, the more massive stars evolve more slowly than the less massive stars, stars begin to expand when about 10% or 12% of their hydrogen is exhausted, stars begin as globules or condensations of cold material
The more massive stars evolve more slowly than the less massive stars.
Spectroscopic studies of Cepheids show that their changes in brightness are correlated with changes in
size.
The "helium flash" occurs at what stage of stellar evolution?
Low mass stars as they become red giants.
If we know only the period for a Cepheid variable star, we can estimate its
absolute magnitude

or luminosity from the Period-Luminosity Relation.
What is not about the same for each star in a cluster?
Mass

The mass for each star in a cluster is different. It is this factor that leads to the variety we see in luminosity and color among different stars in a cluster.
What is Cygnus X-1?
A leading candidate for being a black hole.
Most methods for determining the distances to stars which are too far away for the use of the trigonometric parallax method are based on
comparison of a star's apparent magnitude with an estimate of its absolute magnitude.
A cloud fragment in a star forming region that is too small to form a star most likely becomes:
a brown dwarf.
Which of the following would be considered to be a correct spectral type and luminosity class for our Sun?
G2V
The Crab Nebula is
the debris of a supernova.

in constellation of Taurus
Some regions of the band of the Milky Way appear dark in the night sky because:
stars in that direction are obscured by interstellar dust.
Possible final stages for the evolution of stars are thought to be
black holes
neutron stars
pulsars
white dwarfs
all of the above
all of the above
Which of the following are not intrinsic type variable stars?
Eclipsing Binary

The variations seen in an eclipsing binary are completely due to the viewing angle of the observer on Earth.
A binary system cannot be seen as an eclipsing system if
its orbital plane is perpendicular to the line of sight.
The variable star Algol is a classic example of a/an
Eclipsing binary
Which of the following stars has the greatest luminosity?
A5 IV
M3 III
K9 V
F9 Ia
B8 V
F9 Ia

In this question, the spectral type is secondary because you have been asked about the luminosity. The luminosity class is the indicator here and type Ia are by far the most luminous stars we observe with an absolute magnitude of about -8.
What is the likely final fate of a star whose mass is 1.1 solar masses after it has finished its main sequence life?
It will shrink and become a white dwarf.
A body is heated until it appears yellow in color. It is then heated further until it appears to be bluish in color. The amount of red light it gives off _____________ as the body becomes blue.
increases

As a heated object increases in temperature, it will radiate more energy at every wavelength.
What is the size of a typical white dwarf?
.01 solar radii

A typical white dwarf is about one hundredth the size of the Sun. This is about the same size as the Earth.
The center of our Galaxy is located in the direction of the constellation of
Sagittarius.
The fact that the Sun is far removed from the center of our Galaxy was first conclusively demonstrated by a study of the distribution in space of
globular clusters.
What is the 21-cm line?
A radio wave produced by neutral hydrogen
Which of the following is not one of the Hubble type of galaxies?
Barred Spiral
Elliptical
Spiral
Hyperbolic
Irregular
Hyperbolic
The Magellanic clouds seen in the southern hemisphere are classic examples of
irregular galaxies.
____________ clusters are generally located near the plane of the Milky Way.
Open
The distances to the nearer galaxies like M33 in Triangulum are based primarily on observations of the periods of the ____________ which can be seen in these nearer galaxies.
Cepheid variable stars
Which of the following is almost never found in the Galaxy's halo?
Emission nebulae
A quasar is now thought to be
a very luminous active galaxy at a very large distance away from our Galaxy.
What do we believe to be the central engine for an active galaxy?
A supermassive black hole
The Hubble Law allows astronomers to estimate the age of the Universe. Currently, the best estimate for this age from the Hubble Law and the Hubble Constant is about
14 billion years.
The distance to the bright quasar, 3C 273, is estimated to be about
2 billion light years.
What does the Hubble Law measure?
The rate of expansion of the Universe.
The spectrum of the cosmic microwave background shows a constant and nearly isotropic blackbody temperature of
2.7 K
Isotropy and homogeneity, taken as assumptions regarding the structure and evolution of the Universe, are known as
the Cosmological Principle.
What is the singularity that is often mentioned when talking about a black hole?
A point of infinite density
Recent data from distant supernovae indicate that
the expansion of the Universe is speeding up.
One wavelength that would be appropriate to monitor in SETI research would be
21 cm

The 21-cm wavelength lies in a low noise portion of the spectrum and would be useful for monitoring in SETI research.
At the present time, the value of the Hubble constant is
thought to have a value very close to 70 km/s/Mpc.
Which object is most likely to host planets supporting life as we know it?
Low-mass main sequence stars
The most distant objects which we can observe appear to be
quasars
Which of the following distance measurement methods (which do not include the Hubble relation) extends furthest into the cosmos?
Measurements of Type Ia supernovae
The orbit of the Earth about the Sun defines a plane in space. The orbital plane between the Earth and Sun is referred to as the:
ecliptic

We see the Earth's orbital motion as the apparent daily motion of the Sun through the sky.
You are on a strange planet. You note that the stars do not rise and set, but circle around parallel to the horizon. Then you travel over the surface of the planet in a straight line for 4,500 miles and find that at this new place the stars rise straight up from the horizon in the east and set straight down in the west. (Hint: Think about how your position has changed on the planet) The circumference of the planet is:
18,000

During your observations, you moved from the equator to one of the poles on this planet in 4,500 miles. This is one fourth of the total circumference of 18,000 miles.
Although the stellar constellations are of very ancient origin, they still are useful to modern astronomers:
for identifying stars and designating locations on the sky.
In 1928 the International Astronomical Union divided the entire sky into __________ officially recognized constellations.
88
When Venus has an elongation that is 20° westward from the Sun, it is then visible:
as a morning star.

If Venus is westward of the Sun, it will set before the Sun and be visible as a morning star.
The normal night to night motion of the Moon and planets relative to the background stars is
toward the east

The prograde motion of the Moon and various planets from night to night is from west to east relative to the stars.
At new moon the Earth would appear to an observer on the Moon to be at __________ phase.
full

The phase of the Earth as viewed from the Moon is always just opposite of the observed moon phase seen on the Earth.
First used a telescope to observe the heavens in 1610.
Galileo
Wrote a series of books called the Almagest in which the epicycle theory of the solar system is described in great detail.
Ptolemy
Compiled the most accurate set of naked eye positional observations of the planets that had ever been made up to his time (1600 A.D.).
Tycho Brahe
Discovered the four large moons of Jupiter by direct observation.
Galileo
Wrote the book De Revolutionibus Orbium Coelestium published in 1543.
Copernicus
Was the first person known to suggest the heliocentric model for the solar system.
Aristarchus
Used eclipses of the moons of Jupiter to estimate the speed of light.
Roemer
Discovered the three laws of planetary motion.
Kepler
Formulated the law of gravitation, the laws of motion, and the nature of light.
Newton
Made a remarkably good estimate of the circumference of the Earth during the second century B.C.
Eratosthenes
Suppose you are at the Tropic of Cancer, which has a latitude of 23.5 degrees. The altitude of the north celestial pole as seen from your position is:
23.5 degrees
Suppose you see the Moon in the sky one evening. The next evening, it will have moved:
to the east
Observation of the shift of a star's spectrum toward the red or the blue enables us to determine the star's:
radial velocity
Name the second most abundant element in the Sun.
helium
If a telescope with an objective lens of 10-foot focal length is used with an eyepiece of 1/4 inch focal length, the resulting magnification will be:
480x

10-feet = 120 inches. 120/0.25 = 480x
Orange light is of ______________ than violet light.
lower frequency and longer wavelength
The planet that rotates on its axis with a period almost identical to that of the Earth is:
Mars
Jupiter's 55 or more small outer satellites (moons) appear to be:
asteroids captured by Jupiter.
Which kind of process, as a net result, supplies the energy of our Sun?
Hydrogen atoms are converted to helium through fusion.

Energy in the Sun is released as hydrogen atoms are converted to helium through fusion.
The temperature of the solar photosphere is about:
5800 K
How was Uranus discovered?
By accident, by an astronomer who was conducting a sky survey
Moon of Neptune with a thin atmosphere
Triton
Earth
The Moon
Galilean satellite with sulfur volcanoes
Io
Moon of Saturn that resembles the "Death Star"
Mimas
Mars
Phobos
Moon of Saturn with a thick atmosphere
Titan
Largest rocky surface of any known satellite
Ganymede
Innermost Galilean satellite
Io
Pluto
Charon
Geologically diverse satellite of Uranus
Miranda
Highest albedo of any solar system object
Enceladus
First orbited by Borman, Lovell, and Anders in 1968
The Moon
Large satellite of Jupiter with possible oceans of water under a layer of ice
Europa
Moon of Neptune with a retrograde orbit
Triton
Shepherd moon of Saturn
Pandora
The Zeeman effect describes what changes in spectral lines?
Line splitting due to intense magnetic fields
Which of these telescope qualities is least important to an astronomer for observing stars? resolving power, light gathering power, magnifying power, the ability to photograph or measure for long periods of time, the ability to aim the telescope in different directions
magnifying power
Suppose you are at the equator which has a latitude of 0 degrees. The altitude of the north celestial pole as seen from your position is:
0 degrees.

The altitude of the north celestial pole is always the same as your latitude in degrees.
Because of precession on the Earth, the:
celestial poles gradually change position among the stars.
Which kind of object has the greatest average density? Red giant, Main sequence, White dwarf, Neutron star, Red super-giant
Neutron star
Which kind of process, as a net result, supplies the energy for the stars?
Hydrogen is converted to helium through fusion.
Stars at the left-hand end of the main sequence have which one of these?
Large mass
The Crab nebula is material blown off a ______, which was observed by the Chinese in 1054 A.D. At its center we now observe a ______.
supernova, pulsar
How many stars of 7th magnitude in a small cluster would it take for the cluster to appear as bright as a single 1st magnitude star?
251

The magnitude difference between the star cluster and a first magnitude star is six. The brightness difference is then 2.51 x 100 or a factor of 251.
Which is not a characteristic of a red giant? Nearly depleted hydrogen fuel in the core, Contracted stellar core, Iron being formed into heavier elements, Cool stellar exterior, Expansion of the outer layers of the stellar atmosphere
Iron being formed into heavier elements
Which of these features is not characteristic of nuclear fusion? It is a plentiful energy source, Four hydrogen atoms produce one helium atom (net result), Neutrons and positrons are produced, High temperature is needed to overcome electrostatic repulsion, Large, radioactive nuclei are produced as waste products.
Large, radioactive nuclei are produced as waste products.
A good way to estimate the distance of a distant star cluster is to:
compare its observed H-R diagram with a standard H-R diagram.

Distance determinations generally depend on comparing apparent magnitudes with a good estimate of the absolute magnitude. In this case, the observed H-R diagram provides the apparent magnitudes and the standard H-R diagram is an estimate of the absolute magnitude.
What characteristic is the same for all stars in a star cluster?
Age

Factors that are assumed to common to all stars in a cluster are age, composition, and distance.
Name the second most abundant element in an ordinary star.
helium
The early experiments designed to search for solar neutrinos suggested:
probable difficulty in our theories of stellar interiors.

The early experiments designed to search for solar neutrinos showed that there were many less detected than expected. This lead to serious discussions to evaluate what was believed about conditions in stellar interiors. It turned out that scientists did not know as much about neutrinos as had been thought.
Which of these is not a possible final stage of stellar evolution? White dwarf, T Tauri stage, Black hole, Neutron star, Pulsar
T Tauri stage

The T Tauri stage is an early step in the life of some stars.
What two observations of an object allow for a determination of the Milky Way's mass?
An object's velocity and distance from the galactic center

An object's velocity and distance from the galactic center are orbital parameters along with Kepler's third law that can be used to estimate the mass of a galaxy like the Milky Way.
One wavelength that may provide contact with extraterrestrial civilizations is found at:
21 cm.

The 21-cm wavelength is located at the 'water hole' in the galactic background and thus may provide a point of contact for extraterrestrial civilizations.
If an object is moving toward you, what effect do you observe in the spectrum of that object?
It appears blue-shifted.
In the Drake equation, a technical civilization is considered to be:
a civilization that can communicate over interstellar distances.
Globular clusters:
form a halo concentric with the center of our Galaxy.
Suppose that in the spectrum of a star the spectral lines are observed to be alternately single and then double in a periodic fashion. The star is probably:
a spectroscopic binary.
If a telescope with an objective lens of three-foot focal length is used with an eyepiece of 1/4 inch focal length, the resulting magnification will be:
144x.

Three feet is equal to 36 inches. The resulting magnification is 36/0.25 or 144x.
"Conservation of angular momentum" means that a spinning body tends to:
keep spinning.
The North Star does not appear to move during the night because:
it lies approximately over the northern axis of the Earth.
What would Jupiter have needed to have become a star?
More mass
Of the following types of radiation, which has the smallest (i.e., the least energetic) photons or quanta? Violet light, Infrared, Radio waves, Red light, X-rays
Radio waves
Sunspots are associated with distortions in the Sun's:
magnetic field.
How do the escape velocities of the Jovian planets compare to those of the terrestrial planets?
The Jovian planets have much higher escape velocities.
Shapley found that the nucleus (or center) of our Galaxy is located in the direction of the constellation:
Sagittarius.
Cepheid variable stars are useful as distance indicators because they show a definite, simple correlation between their period of light variation and their:
average absolute magnitude.
The constellations that are visible in the early evening gradually change throughout one year due to the:
revolution of the Earth about the Sun.
Ten parsecs is the standard distance that has been selected as the basis for defining the astronomical scale of:
absolute magnitudes.
Intrinsic variable stars often found in globular clusters are known as __________ stars.
RR Lyrae
All stars of spectral type G2 have approximately the same:
temperature.
On March 21, the right ascension of the Sun is about:
0 hours.

Since the Vernal Equinox is on March 21, the right ascension of the Sun is about 0 hours.
Galileo discovered all of the following except:
the phases of Venus, stars too faint for the naked eye to see, sunspots, the planet Uranus, the four largest satellites of Jupiter.
the planet Uranus
When the Moon is at third quarter, what time will it rise?
Midnight
A galaxy is at a distance of one billion light years. Which of the following is true?
We see the galaxy the way it was one billion years ago.
Which of these is the greatest distance?
One light-year, One parsec, One billion miles, The distance from the Earth to the Sun, The distance out to the planet Pluto
One parsec

One parsec is more than three light-years. All of the other distances are much smaller.
The minor planets (asteroids) in general follow orbits that lie between the orbits of:
Mars and Jupiter.
For what is an interferometer used?
To improve the angular resolution of radio telescopes
Quasars have their distances measured by what technique?
Hubble Law
How many stars of the sixth magnitude would equal the brightness of a star of the first magnitude?
100

Sixth magnitude is 5 magnitudes fainter than first magnitude. A difference of five magnitudes is a difference of a factor of 100 times in brightness.
A star with a spectral type of B2V would be referred to as which of the following? Lower main sequence, Red supergiant, Upper main sequence, Blue supergiant, Red giant
Upper main sequence
Would the Moon be a good place to do astronomy?
Yes, because the Moon lacks an atmosphere.
Of the many complex molecules found in interstellar space, most are based on which element?
Carbon
Ultraviolet radiation is of __________________ than red light.
higher frequency and shorter wavelength
Pair production can occur if:
the energy of two photons is greater than the combined mass-energy of a particle-antiparticle pair.
Which of the following spectral types is the hottest? G8, G9, F1, F2, F3
F1
Beyond 100 parsecs, the distances determined by the method of trigonometric parallaxes become very unreliable because:
the parallax angles become too small to measure accurately.
All eclipsing binaries are also:
spectroscopic binaries.

All eclipsing binaries are also spectroscopic binaries with a low orbital inclination so that the eclipses are visible during each orbital period.
The time required for a photon to travel across our Galaxy is about ____________ years.
160,000
What do all kinds of electromagnetic (i.e., radiant) energy have in common?
All have the same speed in a vacuum
Callisto
Jupiter
Charon
Pluto
Titan
Saturn
Triton
Neptune
Enceladus
Saturn
Mimas
Saturn
Europa
Jupiter
The Moon
Earth
Miranda
Uranus
Phobos
Mars
All of the following may be used to estimate the solar surface temperature except: Wein's law, Kepler's laws, the Stefan-Boltzman law, Planck's law, Solar spectral type and color.
Kepler's laws.
Which type of galaxy has a stellar disk, but without gas or dust?
S0

The S0 or lenticular type galaxies have a stellar disk, but without gas or dust.
The so-called "cosmological principle" is simply the idea that the basic large-scale features of the Universe:
are the same regardless of location.
Which of the following are not found in the Galaxy's spiral arms?
Young star clusters, O and B stars, Globular clusters, Emission nebulae, Dust lanes
Globular clusters
The apparent nodding or wobbling motion of the Moon as it orbits the Earth is called
libration.
Boston is 90° east of Hawaii. If it is noon in Hawaii, in Boston it would be about:
sunset.

The 90° is one fourth of the way around the Earth or 6 full time zones. If it is noon in Hawaii, in Boston it would be about sunset since it is about 6 hours later.
The observed slowing of a clock in the vicinity of a black hole is a prediction of:
general relativity.
The Ptolemaic system accounts for retrograde motion by:
having the planets travel on epicycles.
What do we learn from the Doppler shift when we observe the spectrum of a star?
The star's radial velocity
Which of the following are not intrinsic variable stars? Novae, RR Lyraes, Cepheids, Eclipsing variables, Miras
Eclipsing variables
Why does a star of type G5 have many absorption lines in its spectrum due to metallic elements such as iron, silicon, titanium, etc., while a star of type B5 shows very few lines of such elements?
The B star is very hot and nearly all of its metallic atoms are ionized, which makes them incapable of absorbing photons having visible wavelengths.
The gravitational attraction between two bodies depends on the distance, r, between them. The attraction varies with the distance and is proportional to:
1/r^2.
The Sun rotates once in approximately:
one month.
A star that is responsible for causing a nebula to fluoresce (i.e., emit an emission spectrum) is most likely a star of type:
O or B.
In general, the tail of a comet streams away from the comet in a direction:
away from the Sun.
The ancients thought that rest (i.e., no motion) was the natural state for a material body. Newton's ___________ law states that uniform linear motion is just as natural as rest.
first
The "helium flash" occurs at what stage in stellar evolution?
Red giant
A given meteor shower, like the Leonids:
is visible on approximately the same date each year.
A star that shows evidence of molecules in its spectrum would be considered:
very cool.
The Pleiades cluster of stars is an excellent example of a:
galactic or open cluster.