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Astronomy 106 Final Exam

Astronomy final
STUDY
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What angle would Eratosthenes have measured had the Earth been flat?
0 degrees
A constellation is
A region of the sky outlining a given set of stars
We expect to observe the sun along a path known as the
ecliptic
If a star has a declination of +41'30", then from here in St. Cloud, we would expect the star to transit out meridian at what elevation angle above the local horizon?
About 86 degrees above the southern horizon
The solar day is __________ the sidereal day
longer than
The four seasons on Earth are a result of
tilt of the Earth's axis
The vernal equinox
is a day of equal sunlight and darkness
A solar eclipse can only happen during
a new moon
The length of a sidereal day is determined by
the time between transits of a fixed star
The first quarter moon rises about noon today; what will its phase be, and when will it rise tomorrow?
waxing gibbous, 1pm
If one complete hemisphere of the moon is always lit by the sun, why do we see different phases of the moon?
The Moon shines by reflected light
When the sun is "in Gemini," the most prominent constellation of the zodiak at midnight is
Capricornus
If Earth had the radius of Mars, would the parallax angle increase or decrease?
Decrease
Sirius has a parallax of 0.38", while Alpha Centauri's is 0.77". Alpha Centauri is about __________ as Sirius.
half distance
The vernal equinos is just now entering Aquarius. In what constellation will it lie in the year C.E. 5000?
Capricornus
The star Thuban in Draco
was an excellent pole star in 3,000 BC.
A planet whose distance from the sun is 3 AU would have an orbital period of how many Earth-years?
sqrt(27)
About what fraction of your weight on Earth would you feel on the Moon?
1/6
Copernicus was the first to come up with the geocentric model
False
If we see a bright point of light in the sky that changes its position bit by bit over several nights with respect to the constellations, it is probably
a planet
Planets actually stop and move backward during retrograde motion
False
According to Copernicus, retrograde motion for Venus must occur around
inferior conjunction, when it passes between us and the Sun
Which was not seen telescopically by Galileo?
stellar parallax
When a planet's orbit takes it closest to the sun, it's called
perihelion
Ptolemy's model was ___________, with Earth fixed in the center of the universe
geocentric
According to Newton's three laws, planets orbit the Sun due to
gravity
According to Kepler, a planet moves __________ when at aphelion versus at perihelion
slower
A wave with period of .01 seconds has a frequency of __________ Hz
100
The electromagnetic spectrum includes
infrared, X-ray, visible, radio, ultraviolet
A surface at 750K would emit most energy in what band?
infrared
What is the surface temperature of the Earth when water just begins to freeze, in Kelvin?
273
In what regions of the EM spectrum is the atmosphere transparent enough to allow observations from the ground?
FM, near infrared, visible
A star much hotter than the sun would appear to be __________ in color
bluer
Astronomers use spectroscopic information to determine which of the following?
relative motion, chemical content of the surface, temperature
The spectrum we see from the sun is
absorption
A red photon has higher energy than a blue photon
False
UV radiation causes more cellular damage because of its longer wavelength and lower energy
false
As white light passes through a prism, the red (longer) wavelengths bend less than the blue (shorter) wavelengths, forming the rainbow of colors.
true
The two forms of EM radiation that experience the least atmospheric opacity are
light and radio waves
The radiation our eyes are most sensitive to lies in the color
yellow-green at 550nm
In general, the spectral lines of molecules are
more complex than those of atoms
In a hydrogen atom, the transition from the 2nd to the 1st excited state will produce
the bright red Balmer alpha emission line
The observed spectral lines of a star are all shifted towards the red end of the spectrum. This is an example of
the Doppler effect
If the rest wavelength of a certain line is 600nm, but we observe it at 594nm, then
the source is approaching us at 1% the speed of light
Order the planets according to mass from smallest to largest
Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, Jupiter
Order the planets according to orbital distance from the sun from closest to farthest
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Name the terrestrial planets
Mercury, Mars, Earth, Venus
Name the jovian planets
Jupiter, Saturn, Uranus, Neptune
Planetary orbits
are almost circular, with low eccentricities
The total mass of all the known asteroids would make a planet the size of earth
false
The asteroid belt is located
between Mars and Jupiter
The Kuiper-belt is located
beyond Neptune
The __________ typically have strong magnetic fields
jovian planets
The most plausible theory for the formation of our moon is
impact
Comets typically form bright tails when close to the sun, while asteroids do not. This is because
comets have more ice in them, which boils off to form the tail
Comets seem to spend most of their lives in the
Oort cloud
Due to their great masses, all four Jovian worlds are much denser than the Earth
false
Barringer Crater in Arizona is an example of a meteorite impact
true
Most astronomers now believe the demise of the dinosaurs 65 million years ago was caused by a large asteroid impacting the Yucatan peninsula area
True
Carbonaceous asteroids contain fragile organic molecules
true
We would expect other planets beyond our own solar system to orbit the equators of their home stars
true
Which planet by itself contains the majority of mass of all the planets?
Jupiter
The largest asteroid we know of, and probably the only one to be a spherical "world" is
Ceres
How much advance warning did we receive of the closest approach of asteroid 2002 MN?
none
The Oort cloud is believed to be
a spherical cloud of cometary nuclei far beyond the Kupier Belt
Tides on Earth are created by
gravitational force of the Moon and Sun
Order the layers of the Earth by decreasing density
Core, Mantle, Crust, Hydrosphere
If the Moon's orbit were much closer to the Earth, the lunar month would be
shorter
Our understanding of the structure of the Earth's mantle and core comes mostly from the study of
earthquakes
If the Earth kept its current atmospheric pressure but did not experience a greenhouse effect
the oceans would mostly freeze over
If the surface temperature of the Earth rises substantially, the amount of water vapor in the atmosphere would
increase
Why is the moon heavily cratered, but Earth is not?
The Moon has no atmosphere
According to the theory of plate tectonics, early dinosaurs were able to walk to almost any part of the Earth's landmass
true
What is not a result of plate tectonics?
the grand canyon
Methane could contribute to global warming if a significant amount more is released into the atmosphere
true
Compared to Earth, the moon lacks a hydrosphere, atmosphere, and magnetosphere
true
Which layer is unique among the terrestrial planets?
hydrosphere
At what phase would you expect to find extremely high and low tides?
new and full moons
The critical part of the atmosphere for protecting life on the ground from excessive UV radiation is the
ozone layer
In noting that the Earth is "differentiated," we mean that
the density increases as you descend downward toward the core
Where is the newest material in the Earth's crust found?
At the edge of tectonic plates
Name three principal divisions of the structure of the Earth's interior
mantle, outer core, inner core
Although it has no liquid water, Mercury has a tidal bulge
true
Scarps on Mercury were probably caused by
the crust cooling and shrinking
Venus' surface temperature cools off at night
false
Saying that Venus rotates "upside down" or has a retrograde motion is pretty much the same statement
true
Radar mapping of the surface of Venus shows evidence for vast oceans at some time in the past
false
What is the main constituent of the atmosphere of Venus?
carbon dioxide
If we tried sending a lunar lander to land on Venus
it wouldn't survive to touch down
The consistency of the surface features of Venus can be explained by
massive planet-wide volcanism at some time in its "recent" past
The evidence for plate tectonic activity on Mars is mostly from
N/A
What is the main constituent of the atmosphere of Mars?
carbon dioxide
The Mars Rover found undisputed microfossils, proving life once existed on Mars
false
Which terrestrial planets lack seasons?
Mercury, Venus
In brightness, Jupiter is second only to the planet __________ most of the time
Venus
Jovian planets exhibit extensive tectonic activity
false
What would Jupiter have needed to be a star?
enough mass to make the planet hotter
Jovian planets are mostly __________ below the outer atmosphere
liquid
We base our estimates for the rotation rate of the Jovian planets on what property?
magnetic field rotation
In keeping with its Greek god, Neptune probably contains a lot of water, in a slushy mantle ocean
true
Uranus' rotation axis is tipped over 98 degrees, so its magnetosphere is tipped over the same amount
false
The Galileo mission put a spacecraft into orbit around Jupiter. How did it do this?
Used a gravity assist from Venus and Earth
Small deviations in a planet's orbital motion
imply the nearby presence of a massive body
Compared to Saturn, Jupiter is about
three times more massive and denser
The two outer Jovians appear bluish in color because
methane gas in their atmospheres absorbs red light well
In the telescope, __________ shows the most turbulent atmosphere with changes easily seen
Jupiter
The oblateness of the Jovian disks refers to their __________ equatorial diameters, compared to the polar diameters
larger
The oblateness of the Jovian disks is caused by their
rotation
Because it has a higher percentage of __________, Neptune appears even bluer than Uranus
methane
Which of the moons is bigger than Mercury?
Ganymede
The source of energy for Io's volcanism is assumed to be
tidal stresses
What would you weigh on the surface of Ganymede, compared to your weight on Earth?
14%
The estimated density of Ganymede is greater than that of Io because it is more massive
false
The moon Triton is expected to be destroyed within 100 million years because
it has a retrograde orbit
In terms of composition and density, the atmosphere of Titan is closer to our own than any other place we have found in the solar system
true
Methane drives the weather on Titan, for there it can be liquid, solid, or gas
true
The tectonics we see on Triton are similar to grooves on Ganymede
true
Spacecraft have imaged erupting volcanoes on Io and Triton
true
The haphazard terrain of Miranda suggests it was broken up by impact after it had differentiated, then fell back together randomly
true
The surface of Saturn's moon Enceladus is the most reflective of any in the solar system, suggesting very fresh ice is exposed
true
All four ring systems orbit the equators of the Jovian planets outside their Roche limits
false
A resonance with Mimas clears out the ring particles from Cassini's Division
true
Which element is critical to the formation of the volcanic surface of Io?
sulfur
The mare on Ganymede were formed by
water erupting and spreading over the surface
Of the Jovian satellites, which shows the oldest, most cratered surface?
Callisto
Why are the rings of Saturn so bright?
they are made of young, fresh water ice.
If Saturn takes about 30 years to orbit the Sun, and its rings were seen edge-on in 1995, when will they appear most open at solstice?
2002
The shape of the 1st quarter phase of the moon is caused by the
direction from which the sunlight strikes the moon
If the moon was 3rd quarter last Saturday, what will it be this Saturday?
At or very near new
If we see a first quarter moon today, what will people on the other side of the Earth see later today?
first quarter moon
When does the moon rise throughout various phases?
New - 6am
1st quater - noon
Full - 6pm
3rd quarter - midnight
Which features are older: flow channels or eroded craters?
eroded craters
What is the name of the largest canyon on Mars?
Valles Marineris
What kind of pressure does Mars' atmosphere have?
thinner than Earth's
Which are older: uneroded craters or eroded craters?
eroded craters
What is currently considered to be the most likely cause of the flow channels?
water
What caused some of the erosion on the eroded craters?
wind and/or flowing water
Sort Mars' surface features by age
eroded craters, flow channels, uneroded craters
There were some impact craters created after the flow channels were formed
true
How does the tilt of Mars compare with Earth?
about the same
How do seasons on Earth compare with Mars?
about the same
Is the temperature difference on Mars between + and - 45 degrees larger/smaller than on Earth?
larger on Mars
There is a lag time between when the sun is highest in the sky and when the average temperature is hottest. What causes this?
water takes time to heat up/cool down
Which Jupiter moon revolves fastest?
Io
The mass of Jupiter is greater than the sun.
false
Continuous spectra
A spectrum in which all of the wavelengths is present
Emission spectrum
Produced by an excited gas
A redshift of a set of spectral lines indicates
Something is moving away from you
Spectroscopy is limited to just the visible spectrum
false
The Sun moves the highest in the sky at the summer solstice.
true
The Moon goes through a complex cycle of minima and maxima over a period of ______
18.5 years
Venus was considered
a goddess
What planet is closest to the same size as Venus?
Earth
What was the spacecraft that mapped the surface of Venus?
Magellan
What technique was used to obtain the most accurate image of the sufrace of Venus?
radar
What causes the high temperatures on Venus?
carbon dioxide
What is the distibution of craters on Venus?
even
The age of the surface was considered to be ...
the same over the entire surface