ASTR 111 Becker | Final Exam Review
The south celestial pole is located at celestial coordinates
0 hours RA, -90 degrees DEC
Which of the following points in the sky is located on the celestial equator
0 hours RA, 0 degrees DEC; 12 hours RA, 0 degrees DEC
The clouds observed on Jupiter and Saturn have rotation periods that vary with latitude. This is called ________ motion. The motion of the Great Red Spot on Jupiter is driven by ________
differential; the shear motion of the surrounding belts
Consider the equation F = ma, where F is the applied force, m is the mass of the object, and a is the resulting acceleration. If we ________ while holding m constant, we ________
double F and double a; halve F and halve a
The Nebula Theory of the formation of the solar system
early solar nebula was a large cloud that spun slowly, beginning to shrink due to its own self-gravity; Sun forms at center surrounded by rings
Even though it is close to the Sun, Mercury's orbit is not synchronous because
elliptical orbits can't be synchronous
Which astronomer from the Copernican revolution was the first to place the Sun at the center of the solar system to eliminate the need for epicycles
Copernicus
The ________ force causes hurricanes to spin ________ in the Northern hemisphere
Coriolis; counterclockwise
A hot, thin gas produces ________. Emission and absorption lines can be broadened due to ________
emission lines; high temperature and strong rotation
The Earth's surface is heated by optical radiation from the Sun, and it cools mainly by
emitting infrared radiation
Describe Neptune
Distance: 30.1AU Radius: 4 Mass: 17 Rotation: 0.802 days Moons: 8 Orbital Inclination: 1.774 Orbital Eccentricity: 0.0097 Obliquity: 29.56 degrees Density: 1.64 g/cm^3
Describe Pluto
Distance: 39.5AU Radius: 0.18 Mass: 0.002 Rotation: 0.267 days Moons: 1 Orbital Inclination: 17.15 Orbital Eccentricity: 0.2482 Obliquity: 119.6 degrees Density: 2.03 g/cm^3
Describe Jupiter
Distance: 5.2AU Radius: 11 Mass: 318 Rotation: 0.411 days Moons: 16 Orbital Inclination: 1.308 Orbital Eccentricity: 0.0483 Obliquity: 3.12 degrees Density: 1.33 g/cm^3
Describe Saturn
Distance: 9.5AU Radius: 9 Mass: 95 Rotation: 0.428 days Moons: 18 Orbital Inclination: 2.488 Orbital Eccentricity: 0.0560 Obliquity: 26.73 degrees Density: 0.69 g/cm^3
In the Ptolemaic and Copernican models of the universe, respectively, the objects in the universe in order of increasing distance from the center are:
Earth, Moon, Mercury, Venus, Sun, Jupiter, Saturn; Sun, Mercury, Venus Earth, Mars, Jupiter, Saturn
In Ptolemy's model of the solar system, the ________ is at the center and ________ motion of the planets is explained using ________
Earth; retrograde; epicycles
Interferometry is the process that uses two or more small telescopes separated by a large distance to
improve the resolution to that of a telescope with a size equal to the distance between the telescopes
Which astronomer from the Copernican revolution carefully analyzed and plotted Tycho Brahe's data and deduced the three laws of planetary motion
Kepler
Radio astronomy can be performed
in poor weather, during the day, from the surface of the Earth, and at night
The idea that Pluto is an escaped moon is called into doubt by the fact that
Pluto has its own moon Charon
Galileo's observations of the full phase of Venus were inconsistent with the Ptolemaic model of the solar system because
in the Ptolemaic model Venus is always closer to the Earth than the Sun is
If the distance between two objects is increased by a factor of 3, then the gravitational force between them will
increase by a factor of 9
The length of an Earth day is
increasing as a result of the tidal force the Moon exerts on the Earth
The presence of iron oxide on the surface of Mars indicates that the planet ________ because ________
did not differentiate completely; it cooled too quickly
Radio observations of Venus' ________ revealed that the surface temperature is about ________
Planck curve; 750K
Based on the best available evidence, the amount of CO2 in the Earth's atmosphere seems to be
increasing over the last 100 years due to air pollution, destruction of the rain forest, and ocean damage
The greenhouse effect occurs when
infrared radiation is trapped by atmospheric CO2 and H2O
Formation of the terrestrial planets
inner solar system was about 1000K so no ice formed, and heavy elements such as iron combined with oxygen and silicon to form rocky planets
Sun's Core
inner-most layer of the sun; 15,000,000K; energy generated by nuclear fusion
Planetary rings occur ________. Some small moons of matter are able to exist in the same regions as the rings because ________
inside the Roche limit; they are so small that they are held together by electromagnetic forces rather than by self-gravity
Interplanetary debris
is leftover from the formation of the solar system and ranges from large asteroids and comets to microscopic dust
The scientific method can be summarized using the three words
observation, theory, testing
On March 21, the Sun is located
on or near the celestial equator
On September 21, the Sun is located
on or near the celestial equator
Suppose you point a telescope at a star and then clamp the telescope to the ground so that it cant move. If you wait ________, then the telescope will be pointing to a different star with ________.
one sidereal hour; the same declination but one more hour of right ascension
The various gaps observed in Saturn's rings are caused by ________. The Kirkwood gaps in the asteroid belt are due to ________
orbital resonances with Saturn's moons; resonances with Jupiter
Short-period comets
originate in the Kuiper Belt and have periods less than 200 years
Formation of the Jovian planets
outer solar system was only 200K which allowed water vapor, ammonia, and methane to freeze, forming the "iceburg" cores of the Jovian planets
The Copernican principle is important for observational astronomy because according to it
physical laws are the same throughout the universe
Ecliptic
plane of planets
Kepler's Second Law implies that
planets travel with higher speed as they get closer to the Sun
The slow drift of the continents reflects the action of
plate tectonics
Water ice is able to survive near the ________ on the Moon and Mercury which is because ________
poles; it is hidden in deep shadowed craters
Sunspots
produced by the solar magnetic field; areas of gas on the sun's surface that are cooler than the gases around them
According to Stefan's Law, the energy radiated by an object per unit time varies in proportion to T^4, where T is the temperature of the object. This means that if we ________ the temperature, the radiated energy changes by a factor of ________
quadruple; 256
According to Wien's law, the peak of the Planck curve for a 3000K object is
redder than for a 5000K object
Long-period comets
remain as icy, inactive cometary nuclei in the Oort Cloud
If the Earth were not spinning
rotating hurricanes would not form
Seismic ________ waves cannot propagate through the Earth's core, while seismic ________ waves can
shear; pressure
In Newton's theory of Planetary Motion, the shapes of the orbits are due to ________, but in Einstein's theory the shapes of the orbits are due to ________
the force of gravity; the curvature of space-time
If a light source is receding from you at high speed, then the Doppler effect causes
the frequency of the light to be reduced
Tides on the Earth are caused by
the gravitational pull of the Moon and Sun
Based on telescope observations, it is easy to see that the dark regions on the Moon have far fewer craters than the highlands. This led scientists to believe that
the highlands are 4 billion years old and the maria are 100 million years old
The energy values for the electronic excitation levels in an atom are determined by
the number of protons in its nucleus
The mass and radius of Pluto was measured using
the observations of orbits of Pluto and Charon
The internal heating that powers the volcanoes on Io is caused by
tidal forces from Jupiter
Atmospheric blurring is due to
turbulent motion in the Earth's atmosphere
A total eclipse of the Sun is observed from inside ________. A partial solar eclipse is observed from inside the ________
umbra; penumbra
The retrograde spin on Venus and the 98 degree tilt of the spin axis of Uranus are thought to be due to
violent collisions in the past
Comets are made of
ice and rock, similar to the moons of the outer planets
Comets' nuclei are composed mostly of ________ which ________
ice; sublimates into a gas when the comet approaches the Sun forming the coma and tail
The theoretical resolution in arc seconds for an optical telescope with a diameter D = 25m observing at a wavelength of 10^4 Angstroms is ________. This telescope would make observations with a resolution of ________ if it were located on the Moon's surface, and observations of ________ if it were located on the Earth's surface
0.01 arc seconds; 0.01 arc seconds; 1 arc second
Why are all large telescopes reflectors?
1. Mirrors are easy to support accurately from behind because they only require one coated surface 2. Lenses require support at edges and are heavier 3. Folding of primary and secondary mirrors means telescope tubes can be shorter than "straight through" refraction design 4. Lenses produce chromatic aberration, mirrors do not
The theoretical resolution in arc seconds for a radio telescope with a diameter D = 10^5m observing at a wavelength of 5 x 10^9 Angstroms is ________. This telescope would make observations with a resolution of ________ if it were located on the Moon's surface, and observations of ________ if it were located on the Earth's surface
1.25 arc seconds; 1.25 arc seconds; 1.25 arc seconds
The angle subtended by an American dime at a distance of 3 miles is one arc second. From a distance of 9 miles, an American dime therefore subtends an angle of
1/3 arc seconds
The sidereal rotation period of Jupiter's magnetic field is approximately
10 hours
Consider two telescopes, one with a 3in diameter and one with a 12in diameter. The 12in telescope receives ________ times more light energy per second than the 3in telescope
16
Solar Wind
2,000,000K; a stream of electrically charged particles that emanate from the sun's corona
Sun's Convection Zone
2,000,000K; energy is transported by convective turnover
The density of Pluto is ________ which is similar to that of ________
2.0 g/cm^3; Neptune's moon Triton
The sidereal rotation period of Mars is about
24 hours
The stars return to the same positions in the sky every
24 sidereal hours
How high is the North Celestial Pole above the horizon for an observer at a latitude of 25 degrees
25 degrees
How high is the North Celestial Pole above the horizon for an observer at a latitude of 25 degrees North
25 degrees
Consider the accompanying triangle with a base of 25m. Using trigonometry, the result obtained for the height h is
25m(tan(75 degrees)) = 93.3m
Since the average densities of the Moon and Mars are about ________, we conclude that both objects ________
3-4 g/cm^3; do not have a large fraction of iron
One sidereal day is ________ that one solar day
3.9 minutes shorter
Based on radioactive dating of lunar samples brought back to Earth by the Apollo astronauts we now know that the highlands are actually ________ years older than the maria. This implies that ________
5 billion years; the cratering rate in the solar system dropped sharply about 3.5 billion years ago
According to Kepler's Third Law, P^2 = a^3, where P is the orbital period measured in Earth years and a is the length of the semimajor axis measures in astronomical units. For the planet Saturn, a = 15, and therefore its orbital period is
58.1 Earth years
Uranium-238 has a half-life of about 4 billion years and decays into lead. How long will it take for 3/4 of the Uranium to change into lead?
8 billion years
The spin axis of the planet Uranus is tilted by ________ compared to the orbital axis. This causes ________ seasonal variations
98 degrees; extreme
Which astronomer from the Copernican revolution made the best naked-eye observations of the planetary positions? Which astronomer from the Copernican revolution developed the physical laws explaining why the planets follow elliptical orbits?
Brahe; Newton
The most common gas in the atmosphere of Mars and Venus is ________. The most common gas in the atmospheres of Jupiter and Saturn is ________
CO2; H2
Describe Mercury
Distance: 0.39AU Radius: 0.38 Mass: 0.05 Rotation: 58.8 days Moons: 0 Orbital Inclination: 7 Orbital Eccentricity: 0.2056 Obliquity: 0.1 degrees Density: 5.43 g/cm^3
Describe Venus
Distance: 0.72AU Radius: 0.95 Mass: 0.89 Rotation: 244 days Moons: 0 Orbital Inclination: 3.394 Orbital Eccentricity: 0.0068 Obliquity: 177.4 degrees Density: 5.25 g/cm^3
Describe Mars
Distance: 1.5AU Radius: 0.53 Mass: 0.11 Rotation: 1.029 days Moons: 2 Orbital Inclination: 1.850 Orbital Eccentricity: 0.0934 Obliquity: 25.19 degrees Density: 3.95 g/cm^3
Describe Uranus
Distance: 19.2AU Radius: 4 Mass: 17 Rotation: 0.748 days Moons: 15 Orbital Inclination: 0.774 Orbital Eccentricity: 0.0461 Obliquity: 97.86 degrees Density: 1.29 g/cm^3
Which astronomer from the Copernican revolution made the first systematic telescopic observations of the sky
Galileo
Which astronomy from the Copernican revolution made the first systematic telescopic observations of the sky? Which astronomer from the Copernican revolution carefully analyzed and plotted Tycho Brahe's data and deduced the three laws of planetary motion
Galileo; Kepler
Which methods on the list can be used to detect extra-solar planets?
I. searches for periodic Doppler shifts of lines in the spectrum of the central star II. searches for periodic changes in the pulsations observed from a pulsar IV. searches for periodic drops in the light from the central star due to transits by a planet
Which of the items on the list apply to the terrestrial planets?
I. small, dense, rocky, with solid surfaces II. clustered close to the Sun and each other V. weak magnetic fields, slow rotation
Which of the items on the list are Kepler's Laws of Planetary Motion
I. the cube of a planet's semimajor axis is proportional to the square of its orbital period II. planets follow elliptical orbits with the Sun at one focus III. the line between the Sun and a planet sweeps out equal areas in equal time intervals
Which of the items on the list are Newton's Laws of Motion
I. to every action, there is an equal and opposite reaction II. things at rest remain at read and things in motion travel at uniform velocity unless acted on by an external force III. the acceleration on an object is directly proportional to the force acting on the object and inversely proportional to its mass
Which methods on the list have been used to detect planets with masses similar to that of the Earth?
II. searches for periodic changed in the pulsations observed from a pulsar IV. searches for periodic drops in the light from the central star due to transits by a planet
Which of the items on this list were used to discover the retrograde rotation of Venus?
II. the Doppler shift of reflected radar signal
Which of the items on this list were used to discover the 3:2 spin orbit resonance of Mercury?
II. the Doppler shift of reflected radar signals
Which of the items on the list apply to the Jovian planets?
III. large, gaseous, with no solid surfaces IV. spread throughout the outer solar system V. strong magnetic fields, rapid rotation
Which of the items on the list were used to discover the high surface temperature of Mercury?
III. radio astronomy observations of the Planck curve
The densities of the Jovian moons Io, Europa, Ganymede, and Callisto decrease with increasing distance from Jupiter. However, the moons of Saturn do not show this trend. This is because ________
Jupiter radiated much more heat during the formations of its moons than Saturn did, causing more differentiation of the moon system
Which astronomer from the Copernican revolution developed the physical laws explaining why the planets follow elliptical orbits
Newton
Describe the Sun
Radius: 109 Mass: 332,800 Rotation: 25-36 days Moons: 9 Density: 1.410 g/cm^3
In the Copernican model of the universe, the ________ is at the center and the planetary motions are based on ________
Sun; circles
In Kepler's models of the universe, the ________ is at the center and the planetary motions are based on ________
Sun; ellipses
Due to the tidal bulge in the Earth's crust caused by the Moon, the Earth's rate of spin is ________, and the Moon is ________
decreasing; moving away from the Earth
The planets Uranus and Neptune are more blue in appearance than Jupiter and Saturn because
Uranus and Neptune have more methane has in their atmosphere
Venus has no detectable magnetic field because ________. It is surprising that Mercury has a weak but detectable magnetic field because ________
Venus has a very long rotation period; Mercury spins very slowly
The Cassini division in Saturn's ring is due to
a 2:1 orbital resonance with the moons of Mimas
A hot, dense gas at high pressure produces
a continuous spectrum
Saturn's moon Titan is unique because it has ________ composed mostly of ________
a thick atmosphere; nitrogen
When a lunar eclipse occurs, it can be seen from
any place on the night side of the Earth
Amor Asteroids are
asteroids that cross the orbit of Mars
The energy levels in ________ are determined by the electronic structure only, whereas the energy levels in ________ are also affected by rotation and vibration
atoms; molecules
X-ray and gamma-ray astronomy
can be performed only from space
Optical astronomy
can be performed using the Hubble Space Telescope
Asteroids have two main classes of compositions
carbon-rich (C-type) are dark in color and are more ancient silicon-rich (S-type) are light in color and have probably been reprocessed
When white light is passed through a cool, this gas, the photons that are absorbed
cause radiative excitation and are re-emitted in random directions
Chromatic aberration
causes red/blue light to be focused at different points, is not suffered by mirrors, is suffered by lenses, and ruins color photographs
Atoms can be excited as a result of
collisions with other atoms and absorption of radiation
If two planets with the same mass but different temperatures start off with the same amount of hydrogen gas in their atmospheres, then the ________ planet with retain ________ of its hydrogen than the ________ planet
cooler; more; hotter hotter; less; cooler
As we view stars around the North Celestial Pole from Fairfax, they appear to rotate ________ around Polaris while stars in the eastern sky appear to ________
counter-clockwise; rise
Most of the oxygen in the Earth's current atmosphere was
created by plants
The Apollo Asteroids ________, and the Trojan Asteroids ________
cross the orbit of Earth; are located 60 degrees from Jupiter
We see that the densities of the planets ________ as we move outward through the solar system, due to ________
decrease; differentiation, which causes the dense material to stay near the Sun
Jupiter emits about twice as much energy per second it receives from the Sun because of ________. Saturn emits about 3x as much energy per second as it receives from the Sun, probably because of ________
escape of residual heat; ongoing differentiation
Most of the hydrogen in Earth's early atmosphere has
escaped into space
An eclipse of the Moon can be observed only during a ________, while an eclipse of the Sun can be observed only during a ________.
full moon; new moon
Which type of instrument did Tycho Brahe use to make his measurements of planetary positions
giant protractors and straight sighting rods
Sun's Chromosphere
glowing, transparent layer of gas surrounding the photosphere; 4,500K ; transition region of energy
The narrow shape of Saturn's F-ring is caused by
gravitational interactions between two shepherd satellites
Consider the accompanying triangle with a base of 15 meters. Using trigonometry, the result obtained for the height h is
h = 15m(tan(60 degrees)) = 26m
The semimajor axis of an ellipse is
half the width of the ellipse measured across the longest dimension
Currently, Venus is very hot and Mars is very cold. It may be possible for Mars to become Earth-like in the future, but this is not the case for Venus because the water molecules
have been split up by solar radiation with oxygen escaping into space
Blue light has a ________ frequency
high
Helium precipitation occurs on Saturn but not on Jupiter because Jupiter ________. The hypothesis of helium precipitation in Saturn's atmosphere helps to explain its ________ and also the lack of ________ in its clouds
is too warm for helium to condense; high temperature; helium
Because they are the closest planets to the Sun, Mercury, and Venus are generally easiest to observe
just before sunrise and just after sunset
Sun's Radiation Zone
layer just outside the core; 7,000,000K; radiant energy is transferred in the form go photons
Red light has a wavelength of
longer wavelength and a lower energy than blue
The magnetic fields of Earth, Jupiter, and Neptune are thought to be generated in regions containing ________ respectively
molten iron, metallic hydrogen, ionic slush
To track a distant galaxy using a telescope on the equatorial mount, we need to
move the telescope on the right ascension axis
Asteroids are
small rocky bodies that orbit the Sun and have eccentric orbits, spending the majority of their time in the asteroid belt between Mars and Jupiter
Atmospheric convection is caused by
solar heating of the ground, which heats the air near the ground
The ion tail of a comet is ________ while the dust tail is ________ because ________
straight; curved; the dust particles are more massive than the ions
The structure of the Earth's interior has been determined by
studies of seismic waves
The clouds of Venus are composed of droplets of ________. The water that once was on Venus have been ________
sulfuric acid; destroyed due to heat and solar radiation
The first people on Earth to witness a given total solar eclipse see it beginning at ________. The track of the eclipse shadow moves across the Earth's surface from ________
sunrise; west to east
According to Kepler's Second Law, a line connecting the Sun with the planet Jupiter
sweeps out equal areas in equal times
Consecutive full Moons occur every
synodic month
The Condensation Theory of the formation of the solar system
takes the Nebular model and adds dust which cools the nebula by emitting infrared radiation which reduces pressure
The huge Mariner Valley on Mars was formed by ________. The Grand Canyon on Earth was formed by ________
tectonic fracturing; water erosion
The highest high tides occur when
the Earth, Moon, and Sun form a line
The lowest high tides occur when
the Earth, Moon, and Sun form a right triangle
An annular eclipse occurs when the Sun, Moon, and Earth line up, and
the Moon is at its maximum distance from the Earth
Although the Moon and the Sun have about the same angular size as viewed from the Earth, eclipses are relatively rare because
the Moon's orbit is tilted with respect to the Earth's orbit
Sun's Corona
the Sun's outer atmosphere; 1,000,000K; x-rays produced
Helioseismology
the analysis of acoustic waves observed on the solar surface
The theory for the Moon's formation thought to be most likely is
the collision or impact theory
We think that the famous Martian meteorite is from Mars because
the composition of gas trapped inside the meteorite matches that measured by the Viking landers
Some scientists think the organic material inside the famous Martian meteorite is actually due to the contamination on Earth. This is unlikely because
the concentration of organic material increases towards the center of the meteorite
If a light source is approaching you at high speeds, then the Doppler effect cause
the energy of the light to be increased
The Moon and Mercury have no significant atmospheres because
the escape velocity is too low
The planet Mars is easiest to observe during favorable opposition because
the planet is closest to the Earth and the Sun, and it appears full from Earth
The reverse runaway greenhouse effect probably occurred on Mars because
the planet was too cold for CO2 and H2O gas to be retained in the atmosphere to from a thermal blanket
The runaway greenhouse effect probably occurred on Venus because
the planet was too warm for oceans to form and absorb most of the CO2 gas
The 70% albedo of Venus is due to
the reflective cloud layer at high altitudes
The current absence of liquid water on the surface of Mars resulted from ________. The water that used to be on the surface is now ________
the reverse runaway greenhouse effect; under the surface as permafrost
The emission and absorption lines of hydrogen gas occur at ________ frequencies. The pattern of emission and absorption lines ________ the composition of gas
the same; can be used to identify
Aristarchus hypothesized that the Earth revolves around the Sun. Which of the following is a reason that the other Greek philosophers used to reject this idea
the stellar parallax could not be observed
Impact craters on Mercury are generally smaller than impact craters on the Moon because
the surface gravity of Mercury is higher
If the concentration of CO2 in a planet's atmosphere increases
the surface temperature increases because the additional CO2 acts like an extra blanket
Equatorial telescope mounts are convenient when photographing dim astronomical objects like distant galaxies because
the telescope needs to be driven on only one axis to track the galaxy
It is colder in winter than in summer because
the tilt of the Earth's axis causes the Sun to be lower in the sky during winter
Sun's Photosphere
the visible surface of the Sun; 6,000K; energy escapes as radiation
We do not detect shear waves on the side of the Earth opposite from an earthquake. From this evidence, we deduce that
there is a liquid core in the Earth
The density of Mercury is similar to the density of Earth. This implies
there is probably a massive iron core inside Mercury
The channels and outflows features discovered on Mars by Mariner 9 and Mars Global Surveyor show that
there was a huge flood of water from the southern highlands to the northern highlands
Most large telescopes are reflectors and not refractors because
they are difficult to support, difficult to fabricate, and they suffer from chromatic aberration
Meteorites are extremely useful for astronomers because
they make it through the atmosphere to the Earth's surface and they are composed of primordial solar system material
Retrograde motion occurs when a planet appears to move
westward relative to the stars
In the Copernican model of the solar system, retrograde motion of Mars occurs
when the line between the Earth and the Sun passes over the line between Mars and the Sun
If we travelled away from Earth through the galaxy, the constellations
would appear to change slowly