Download Telephone Quizzes for ASTR 200 1999 Revision

Quiz 1
1. Aristarchus boldly concluded that total solar eclipses, with almost exact coverage of the Sun's disk by the
Moon, were possible because the Sun was 20 times larger than the Moon, yet 20 times further away.
Instead of 20, we now know the correct factor to be:





186,000.
3.14159.
1.5108.
400.
100.
2.
The asteroid 2104 Toronto has a=3.193 AU and e=0.133. Its sidereal and synodic periods are, in
that order:





3.193 years, 1.456 years.
5.706 years, 1.213 years.
5.706 years, 0.851 years.
2.168 years, 1.856 years.
3.326 years, 1.430 years.
3.
Mars has a mass equal to 0.107 times that of the Earth, and a=1.5237. Compared to the force the
Earth exerts on the Sun, that exerted by Mars on average is in the ratio:





0.107.
0.43.
4.03.
0.046.
2.17.
4.
The nearest star is at about 1 pc from Earth, and the nearby and brightest star Sirius is at 2.64 pc
from Earth. Expressed in AU, the distance of Sirius is:





544000.
8.15105.
4.89108.
1.496108.
34000.
5.
That the planets move in elliptical orbits was:





proposed by Newton and explained by Kepler.
known since the time of the ancient Greeks although they thought Earth was at the centre.
discovered by Kepler but only confirmed later by Newton.
observed by Tycho.
essential to Copernicus’ heliocentric theory.
6.
If a total solar eclipse occurs with the Moon passing through the ascending node:





a lunar eclipse could occur 3 or 4 months later.
a similar ascending node eclipse could occur two months later.
a lunar eclipse with the Moon at the descending node could occur two weeks later.
a lunar eclipse with the Moon at the ascending node could have occurred two weeks before.
both  and  are possibl
7.
We see the same face of the Moon because:





more or less of it is illuminated as it orbits the Earth.
the synodic month and its synodic rotation period are the same.
the synodic month is longer than the sidereal month.
the Moon’s rotation is locked to the Sun.
the sidereal month and its sidereal rotation period are the sam
8.
If the Moon is 60 Earth Radii from the centre of Earth and takes 27.3 days to orbit, at what
distance must a geosynchronous satellite, which takes exactly one day to orbit, be located?





27.3 Earth Radii.
660 Earth Radii.
1 Earth Radius.
6.6 Earth Radii.
such an orbit is not possibl
9.
Since the Moon moves on a path fairly near the ecliptic, as seen from far northern Canada it
would:





spend roughly two weeks above the horizon and the next two weeks below the horizon.
rise and set every night.
always appear to be near the Sun in the sky.
always appear to be full in summertim
none of the abov
10.
Retrograde motion characterizes the apparent motion of:





all outer planets.
all inner planets.
all solar system objects including Sun and Moon.
Mars and no other planet.
 and 
Quiz 2
1.
A line is observed fitting into a clear sequence of Balmer absorption lines in a stellar spectrum,
and has its wavelength determined as 370.4 nm. What electronic transition created this line?





third level to second level.
270th level to second level.
first level to ionization.
second level to 16th level.
21st level to second level.
2.
Lyman-beta photons involve which energy levels, and have which wavelength?





2, 1, 122 nm.
infinity, 1, 13.6 eV.
2, 1, 103 nm.
6, 7, 122 nm.
2, 1, 21 cm.
3.
The Chandra X-ray observatory can form X-ray spectra between 0.07 keV and 10 KeV energies.
This corresponds to what wavelength range?





2.810-27 to 2.010-29 m.
0.1 to 18 nm.
70 to 10000 km.
13.6 to 91.1 nm.
400 to 660 nm.
4.
How much more light would be gathered by the twin 10 m diameter Keck telescopes than by a
pair of ‘standard’ binoculars having lenses of 50 mm diameter?





200.
2000.
4000.
10000.
4106.
5.
Very large aperture ground-based instruments are primarily built:





to provide magnified images.
to make objects appear closer.
to channel funds into U.S. congressional districts.
to measure a wider spectrum of light from stars.
to collect more light from distant objects.
6.
Reflecting telescopes are preferred at large apertures because:





a large mirror is more attractive to look at than a large lens.
there is no chromatic aberration and large sizes are more feasible at relatively better cost.
large telescope mirrors may be made from inexpensive metal rather than costly glass.
they have chromatic aberration making it easier to obtain colorful photographs.
Newton’s original design established a tradition which has prevailed to this day.
7.
Many radio telescopes may be joined together to form an interferometer with the principal aim of:





increasing the total amount of signal gathered.
comparing the images formed so as to average out defects.
interfering with sources of noise and eliminating them.
having a system redundant against the failures which plague each receiver.
obtaining the highest possible angular resolution in making radio views.
8.
The luminosity of a star is well approximated by that of a blackbody, for which



second.


it is proportional to the temperature and the radius.
it goes up as the square of the radius and the fourth power of the temperature.
the flux is the energy flowing through an imaginary sphere surrounding the entire star in one
9.
Stellar spectra usually have absorption lines since





continuous radiation from deep layers passes through a cooler atmosphere.
clouds of gas in space remove light at certain wavelengths.
the star’s surface absorbs light from space before re-emitting it.
stellar surfaces are uneven, porous, and absorbent.
many elements were discovered after being detected in the solar spectrum.
10.
The exact wavelength at which a stellar spectral line is observed will be determined primarily by:





its change in wavelength as determined by Wien’s law.
collisions with other atoms in the hot gas of the star.
the emitting atom and the velocity of the star with respect to Earth.
the dispersion of the spectrograph.
colour filters which are placed ahead of the spectrograph in the optical path.
the wavelength at which most energy emitted corresponds to the colour ‘black’.
most of the light is given off in the form of spectral emission lines.
Quiz 3
1.
The rings of Saturn





are just inside the Roche limit for Saturn.
make it the only gas giant planet with rings.
are strongly affected by resonance interactions with moons.
are solid and massive.
 and above.
2.
Tidal heating on Io is sustained because it repeatedly comes to the same configuration with respect
to Europa and Ganymede They line up with Io, respectively, after:





2 and 5 orbits of Io around Jupiter.
3 orbits of Jupiter around the Sun.
2 and 4 orbits of Io around Jupiter.
1 and 2 orbits of Io around Jupiter.
1 orbit of Europa around Jupiter.
3.
Planets with a large enough magnetic field to deflect the Solar Wind and allow formation of a
magnetosphere include:





Mercury, Venus, and Earth.
Mercury, Venus, Earth, and Mars.
all metallic asteroids.
Mercury, Earth, and Jupiter.
Mercury, Earth, and Pluto.
4.
The highest elevations in the Solar System, compared to mean elevation on a planet, are found on





Maxwell Montes, Venus.
Olympus Mons, Mars.
Mount Everest, Earth.
Caloris region, Mercury.
none of the above.
5.
The different classes of meteorites are consistent with models of the Earth which feature:





iridium layers.
amino acids.
continental drift and plate tectonics.
differentiation into mantle, crust, and core.
Hirayama families.
6.
‘Highly eccentric’ and ‘highly inclined’ would be terms used by an astronomer to denote:





his supervising professor while completing his doctoral degree.
the shape of the inner Jovian moon Amalthea.
the flattened shape of the planet Saturn.
the solar system model of Ptolemy.
the orbit of Pluto.
7.
Evidence that a comet nucleus is a flimsy ‘dirty snowball’ is provided by





the easy fragmentation of comets when in the strong gravitational fields of other bodies.
spacecraft experiments which have sampled comets directly.
the orbital characteristics of comets.
the presence of the Oort cloud .
the fact that comet tails point away from the Sun.
8.
The small number of craters on Earth and Venus is explained by

their position in the inner solar system, away from the asteroid belt which provides objects to
impact planetary surfaces.

the limestone which covers their surfaces, which shatters without making a distinctive crater.

sulfuric acid, present on both, which chemically obliterates surface features.

protective dense atmospheres.

active geological processes.
9.
Using considerations from the box about synodic and sidereal periods from Unit 1, the 0.319 day
sidereal period of Phobos, and the 1.0 day sidereal period of Mars’ rotation, we can conclude that the
period from one rising of Phobos (in the west) until the next, as seen from the surface of Mars, is





24 days.
0.319 days.
slightly over 5 hours.
slightly over 11 hours.
slightly over 24 hours.
10.
planet
The present-day absence of water, which was seemingly abundant on Mars early in its life as a

is best explained by reference to the canals, which drained it away.

is because Martian organisms once existed and locked it up in carbonate minerals generated from
their shells.

is evidence that the rate of impact of water-bearing comets has slowed dramatically since shortly
after the planets formed.

may be due to a combination of atmosphere loss, and permafrost and ice caps storing water as ice.

is evidence that the Sun has warmed over the life of the Solar System.
Quiz 4
1.
If sunspots are cooler than the rest of the Sun’s surface by 1500 K, what is the wavelength of their
peak emission of light compared to the 500 nm at which the Sun emits?





193 nm longer.
193 nm shorter.
175 nm shorter.
175 nm longer.
no change.
2.
The main sequence lifetime of a star of half the mass of the Sun





is the same as that of the Sun as mass does not affect the lifetime of a star.
is shorter than that of the Sun since there is less fuel to burn.
is longer than that of the Sun because the star generates energy (uses fuel) at a very slow rate.
cannot be discussed as such a star is too small to generate energy.
is meaningless since such a star is smaller than the Chandrasekhar limit.
3.
A cogent argument against the claims of certain UFOlogists that Earth is being visited by beings
from the Pleiades star cluster is that

the bright blue stars of this cluster are unlikely to have planets harbouring life

the H-R diagram indicating an age not sufficient for life to have evolved on planets there.

the dusty reflection nebulosity suggesting that solar systems have not formed there.

the formation of this cluster by a recent supernova which would have killed any advanced life
forms present at the time.

the very large gravitational field of the cluster would prevent any conceivable spacecraft from
leaving the region.
4.
To explain the production of red light from nebulae under the influence of UV photons from
nearby bright stars, we would be dealing with atomic levels in hydrogen which are





HII-OB associations.
found only when it is in molecular form.
energized by photons more energetic than Lyman photons, but emitting with Balmer lines.
associated with reflection.
not found in terrestrial laboratories.
5.
Choose the statement(s) describing the end of the main sequence phase of most stars’ lives.





Hydrogen burning in the core commences.
Surface flux decreases but luminosity rises.
Surface temperature falls and area increases.
all of the above.
only  and  are true.
6.
In looking at H-R diagrams of various types of clusters, what could be said in general as they get
older, and why?

the turnoff point moves upward as more high mass stars form.

the turnoff point moves downward as high mass stars move off the main sequence.

the turnoff point is a remarkably stable point which we can used to align the H-R diagrams and
determine distances, since all stars share fundamental characteristics.

the oldest clusters are metal rich since stellar nucleosynthesis has converted hydrogen to metals.

there are dramatic differences between H-R diagrams of globular clusters and open clusters, which
cannot be explained primarily on the basis of age.
7.
A Type Ia supernova is believed to be

the explosion of a white dwarf, most likely due to mass transferred to its surface from a
companion star.

the explosion of a massive star after silicon burning has produced a core of iron nuclei.

the explosion of a red giant star due to the helium flash in the core.

the collapse of a blue supergiant star to form a black hole.

the collapse of a helium-rich stellar core which has lost its outer layers.
8.
The binary star Delta Equulei is one of the shortest period visual binary stars. The parallax was
long ago measured as 0.066 arcsec, and the period is 5.7 years. What is the mass of each star if they are
equal in mass and have orbital angular semimajor axis of 0.27 arcsec?





5 solar masses.
2 solar masses.
1 solar mass.
0.5 solar mass.
0.1 solar mass.
9.
Two bright blue (both have B-V very near 0) winter stars are Rigel and Sirius, whose V
magnitudes are 0.12 and –1.46 respectively. Recent parallaxes from the Hipparcos satellite are 0.00422 and
0.37921 arcseconds, respectively. MV and the likely luminosity classes for these stars, respectively, are





5.33, I; 6.78, III.
-3.21, III; -2.11, III.
5.77, V; 2.66, V.
-6.75, I; 1.43, V.
-4.32, II; -3.77, I.
10.
The stars in present-day globular clusters do not produce energy using the CNO cycle to allow
hydrogen fusion. This is because





they do not contain hydrogen at their centres.
they are low metallicity stars.
they are low mass stars with relatively low internal temperatures.
 and  above.
 and  above.
Quiz 5
1.
In a static, infinite, and infinitely old universe





any line of sight would eventually intersect a star, so the sky would always be very bright.
gravity would be infinite at all points.
we would expect to see a 3 degree uniform background radiation.
the Steady State Theory would apply.
the cosmological constant would not be needed to explain the structure of spacetime.
2.
In the unified model of active galactic nuclei





general relativity and quantum theory have been unified to explain their activity.
the angle at which a galaxy is observed is critical in determining what we see.
black holes in binary star systems play an important role.
spiral galaxies and elliptical galaxies are seen as stages in galaxy evolution.
 and  are both correct.
3.
Making a radio map of our own Galaxy would not be possible





if the density of interstellar dust was too low.
if both the proton and electron possessed spin.
if radio emitting stars were not commonly found.
without knowledge of the Hubble constant.
if the Galaxy rotated like a solid wheel.
4.
According to the density wave theory

stellar orbits are precessing ellipses which align to form a spiral pattern in galaxies.

there is insufficient light observed to account for the total mass of galaxies.

the universe will expand and contract as its density varies.

spiral structure in galaxies is caused by compressional waves which travel through the interstellar
medium and are distorted by differential rotation.

collisions between stars send shock waves propagating through the interstellar medium within
galaxies.
5.
The most important and accurate ‘standard candles’ for distant galaxies are





RR Lyrae stars.
Sun-like stars since we know the brightness of the Sun so accurately.
Cepheid variables and Type II supernovae for more distant objects.
Cepheid variables and Type Ia supernovae for more distant objects.
actual candles placed on distant mountaintops and observed to calibrate the telescope.
6.
A useful way of stating the dark-matter problem is

due primarily to gravitational effects we know what matter is there but it seems not to give off
enough light.

due to absorption of light by dark interstellar dust we do not know how many other objects are
behind the dust.

interstellar material should be much lighter coloured than it is observed to be.

the universe is dark but this does not matter.

there is an overabundance of observational evidence of black holes.
7.
Early Hubble Space Telescope observations of the Virgo Cluster galaxy M100 showed a Cepheid
star with average mV=25.4 and a period letting us know that MV=-5.8. From spectroscopic studies, the
average redshift of the Virgo cluster is 1404 km/s. From these data, what would be the Hubble constant?





64 km/s/Mpc.
75 km/s/Mpc.
81 km/s/Mpc.
50 km/s/Mpc.
90 km/s/Mpc.
8.
The background radiation, expected to be uniform on the largest scales, actually is slightly warmer
in one direction and cooler in the opposite direction. This is due to





the Milky Way affecting the observations.
the impossibility of calibrating the telescope and removing such variation.
the Big Bang being imaged in the warmer direction.
microwaves amplified by gravitational lensing by intervening matter.
Doppler shifts due to various local motions of the Earth, Sun, and Galaxy.
9.
By the end of the first three minutes, all elements that the Big Bang could form, had formed. Our
present cosmic distribution of elements features





the whole gamut of elements, all created in the Big Bang.
hydrogen and helium, and other elements formed by nucleosynthesis after the Big Bang.
hydrogen created by the Big Bang, and helium and other elements formed only later in stars.
primarily deuterium, which forms hydrogen in interstellar space and heavier elements in stars.
none of the above.
10.
Gravitational lensing in known examples takes place





when a black hole bends light coming from a background object.
when gravity shapes gas into a shape resembling a giant lens.
when light speeds up upon entering the gravitational field of Earth.
when a concentration of mass such as a galaxy or cluster focusses a distant object.
when the telescope optics are distorted due to the effect of gravity.