Astronomy Final Exam
Use the image below to answer the following question. Which labeled object(s) in the image below significantly reflect or scatter blue light particularly at this time of day? (Select all that apply.)
-2 -7
Select the two spectra that represent objects with different temperatures and do not involve absorption or emission. (You must select two figures.)
-6 -3
Match the type of heat transport responsible with each example.
-A bowl of soup cools from the top: convection -An iron skillet gets hot by direct contact with a stove: conduction -A lightbulb filament slowly cools after the light is turned off: Radiation
In which of the following cases is a net force acting on the object? (Select all that apply)
-A moving train coming to a stop. -A spaceship orbiting Saturn in a circular orbit at constant speed. -A soccer ball mid-flight and accelerating back toward the ground.
All of the statements below are true. Which statements are equivalent to Kepler's 2nd law which says that the imaginary line connecting a planet to the Sun sweeps out equal areas in equal times. (Select all that apply.)
-A planet's angular momentum is conserved as it orbits the Sun. -A planet moves faster when it is closer to the Sun and slower when it is further from the Sun.
Sirius (α Canis Majoris) A has an apparent (visual) magnitude of -1.46, an absolute (visual) magnitude of +1.43 and a luminosity of 25.4 L⊙. Rank the following stars from highest luminosity (1) to lowest luminosity (4).
-A star with an absolute magnitude of -1.00: 1 -A star with an absolute magnitude of +2.5: 3 -A star at the same distance as Sirius with an apparent magnitude of +15.0: 4 -A star with a luminosity of 30.0 L⊙: 2
A hypothetical star with the same luminosity of the Sun (1 L⊙) has a parallax angle of 1 arcsecond. Which of the following stars would appear 25 times brighter than this star from Earth? (Select all that apply.)
-A star with the same luminosity and a parallax angle of 5 arcseconds. -A star which is 5 times closer away but just as luminous. -A star at the same distance but with a luminosity of 25 L⊙.
Consider the two star clusters shown below. Select all of the following statements that properly compare an average star in each cluster as seen today. (Select all that apply.)
-Assuming the stars in each cluster formed at the same time, stars in cluster B are older than stars in cluster A. -Stars in cluster B are less massive than stars in cluster A. -Stars in cluster A have shorter life spans than stars in cluster B.
All of the physical principles below are fundamental to the nebular theory. Match each physical principle to an observable in protoplanetary disks around newly forming stars.
-Conservation of angular momentum: The nebula spins faster as it contracts in size -Conservation of energy: the nebula gets hotter as it contracts in size -Conservation of momentum/angular momentum in collisions: The nebula flattens into a disk of material on circular orbits
Arrange the regions of the Sun with 1 being the highest temperature region and 4 being the lowest temperature region. (Not all regions of the Sun are listed)
-Core -Radiative Zone -Chromosphere -Photosphere
Which of the following could occur if the Sun is between the Earth and the Moon? (Select all that apply)
-Full Moon -The Sun is never between the Earth and the Moon
Number the different material in order from most abundant (1) to least abundant (5) in the primordial solar nebula.
-Hydrogen gas -Helium gas -Hydrogen compounds -Rocky minerals -metals
Select all of the statements that are falsifiable (scientifically testable).
-I can teleport to work and back instantaneously. -There are no lakes, seas, or rivers on the surface of Mars today. -My house is haunted by ghosts who make the creaking noises I hear each night.
Select statements that are TRUE regarding Infrared waves and X-rays?
-Infrared waves have a lower frequency than X-rays -Infrared waves have lower energy than X-rays -Infrared waves and X-rays travel at the same speed
Which of the following are true for a sunlike star moving radially toward you at a very small fraction of the speed of light, say 5 km/s? (Select all that apply)
-Its spectrum will show what astronomers call blueshift. -Its spectral features will appear at shorter wavelengths than they would in a laboratory spectrum.
When Jupiter, which is further from the Sun than Earth, is in the portion of its orbit where we see it undergoing apparent retrograde motion. Which statements are true? (Select all that apply)
-Jupiter is slowly moving westward when compared to background stars over several weeks. -Jupiter will be high in the sky around midnight.
All of the following statements are true. Which contribute to the explanation that Jupiter's moon Io is the most volcanically active world in the solar system and Jupiter's moon Europa likely has a larger volume of liquid water than Earth beneath its fractured icy crust? (Select all that apply.)
-Jupiter's moons are more icy than terrestrial planets and ices melt at lower temperatures than rock. -Europa and Io are both experiencing an orbital resonance with Ganymede. -Both moons have eccentric orbits and large differences in tidal forces between their closest approach and furthest distances from Jupiter.
The image below represents an H-R Diagram. Which of the following labels could be used for Box 1 (select all that apply)?
-Luminosity -Absolute magnitude
A star cluster is around 6 billion years old and has a main-sequence turnoff point around spectral type G. Select all of the following types of stars you WOULD certainly see on the main sequence for this cluster today? (Select all that apply)
-M -K
The figure below shows the radial velocity profiles of the host stars of two exoplanets. The two stars are the same size and mass. Which statements below are true? (Select all that apply.)
-Planet B has a more eccentric orbit than planet A. -Planet B orbits faster than planet A. -Each data point in the figure came from measuring the Doppler shift of the star's spectrum.
Which of the following statements contribute to the explanation for the observation that Earth has significantly fewer large impact craters than the Moon? (Select all that apply)
-Plate tectonics and erosion erase ancient craters from Earth's surface but there is no tectonics or erosion on the Moon's surface. -The Moon's surface is older or has remained unchanged for longer than the Earth's surface.
Which of the following observations can NOT be attributed to conservation of angular momentum during star formation? (Select all that apply.)
-Stars with more mass have higher surface temperatures. -Stars fuse H into He in their core. -Stellar masses range from ~0.08 to ~150 M⊙.
The escape velocity for a 100 kg object on the Moon is about 2,380 m/s. Select all of the following statements that are true.
-The escape velocity for a 0.1 kg object is also 2,380 m/s. -A spacecraft would have to go much faster than a bullet (>1km/s) to orbit near the Moon's surface. -The escape velocity from twice the distance from the Moon's center is much less than 2,380 m/s.
Which statements regarding Kepler's third law, p2 = a3 are true? (select all that apply.)
-The orbital period of a planet doesn't depend significantly on the planet's mass. -planets that are further from the Sun orbit at slower average speeds.
Which of the following are required for a planet to maintain an internally generated magnetic field? (Select all that apply.)
-The region generating the magnetic field must be convecting. -The region generating the magnetic field must be an electrically conducting material. -The planet must rotate fairly rapidly (period less than a few days)
All of the following statements are true. Which contribute to the fact that Saturn's rings are so thin? (Select all that apply.)
-The relative speeds of neighboring ring particles is just a few cm/s. -Saturn's rings are densely packed with particles so any particle with a tilted (inclined) orbit will collide with another particle in less than 1 orbital period.
Which of the following can be attributed to Earth's axis tilt? (Select all that apply)
-Warm summers and colder winters. -The number of daylight hours changing over the course or the year. -The Sun rising north of east and setting north of west during the northern hemisphere's summer.
Of the six gases below, which are greenhouse gases? (Select all that apply.)
-Water: H2O -Methane: CH4 -Carbon Dioxide: CO2
This photograph shows a hurricane from space. Why does it have the counter-clockwise swirl? (Select all that apply.)
-because of the Coriolis effect -because it is in the Northern Hemisphere
Which two states of matter are involved in the process of ionization?
-gas -Plasma
Which of the following statements about an astronomical unit (AU) are true? (Select all that apply)
-is the average distance between Earth and the Sun. -AU are used for measuring distances within our solar system. -AU is a unit of distance.
According to the graphs below, which of the following years had the least sunspot activity?
1987
A comet grows tails (plasma tail and dust tail) when it comes close to the Sun. Which of the following diagrams shows a comet's tails correctly oriented as they appear along its orbit?
2
In which case below would you expect the observer to see an absorption spectrum in the visible range?
2
The figure below shows the energy levels of an electron in an atom and the numbered arrows represent transitions between those levels. Which of the following electron transitions depicts an electron absorbing a photon with the largest wavelength?
2
The figures below show a laboratory spectrum of a sunlike star at rest and the measured spectrum of a star. In which case is the star moving toward you?
2
A portion of the spectra from the atmospheres of 3 stars are shown below. Which is the coolest star?
3
The image below represents an H-R Diagram. Which of the regions listed below have stars with the smallest radii?
3
Which position in this diagram represents Earth on the day when the Sun reaches its highest point in the sky in Cape Town, South Africa (southern hemisphere)?
3
The image below represents an H-R Diagram. In which numbered region(s) would you expect to find stars that are fusing hydrogen in their cores and have relatively short lifespans? (Select all that apply)
4
The light-collecting area of a 2-meter telescope is ________ times that of a 1-meter telescope.
4
According to Kepler's third law (p2 = a3), an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to
4 astronomical units.
A certain radioactive element, call it "A" decays into a stable isotope of another element "B". The half-life of A is 1 billion years. If a sample has 4 atoms of A for every 60 atoms of B, which is the best estimate of its age?
4 billion years
Kepler's 3rd law relates a planet's orbital period and its average distance from the Sun (p2 = a3). If a dwarf planet were discovered with an average distance from the Sun of 60 AU, its period would be about ___________ .
400 years.
The image below shows a star field taken in visible light by the European Southern Observatory. There are no intervening nebulae blocking any of the light. Which of the stars labeled below is the coolest at its surface?
6
Carbon-12 has 6 protons, 6 neutrons, and 6 electrons. If another atom has 6 protons, 8 neutrons and 6 electrons, which statement below best describes the difference?
A different isotope
In a scale model of the solar system, if the Earth is represented by a peppercorn, what would best represent the distance from the Earth to the Sun?
A football field.
Which of the following best describes how the greenhouse effect works?
A planet's atmosphere is transparent to visible light but its surface absorbs visible sunlight and returns this absorbed energy to space as infrared light. Greenhouse gases scatter this infrared radiation, which thereby heats the lower atmosphere.
Which of the following is not necessary of a good scientific theory?
A scientific theory must be proven true beyond all doubt to be accepted.
During which phase is the one half of the Moon's surface illuminated by the Sun?
All of the above
Which of the following is the best answer to the question, "Why does the Sun shine?"
As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine.
During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in
Baghdad (Iraq).
Suppose you want to determine the density of a planet orbiting another star which observation methods would be necessary?
Both the Doppler and transit method
Which person below created a model of the solar system that put the Sun in the center, but that was not very accurate because he assumed that the orbits of the planets must be perfect circles?
Copernicus
Suppose you want to determine the mass of a planet orbiting another star which observation methods would be necessary?
Doppler method
Which of the following explains why the stars visible in our sky just after sunset are different from those visible just before sunrise?
Earth rotates once each day.
Which of the following statements describe how objects in the universe have been affected by the expansion of space since the Big Bang? (Select all that apply.)
Galaxies move farther away from each other over time.
What type of meteorite has undergone the most processing by high temperatures and pressures?
Iron meteorites, which have undergone significant heating and differentiation.
Why does the Sun's surface exhibit a pattern of churning and bubbling?
It is due to the convection of hot plasma moving upwards and cooler plasma moving downwards beneath the surface.
What is the meaning of the term "gravitational equilibrium" in the context of the Sun?
It means that there is a balance between the outward push of pressure and the inward pull of gravity within the Sun.
What do astronomers mean by light pollution?
Light pollution refers to light used for human activities that brightens the sky and hinders astronomical observations.
What is the primary mechanism by which the Sun emits most of its energy in the form of visible light?
Like all objects, the Sun emits thermal radiation with a spectrum that depends on its temperature, and the Sun's surface temperature is just right for emitting mostly visible light.
What is the term for a luminous streak of light produced when a meteoroid enters Earth's atmosphere and burns up?
Meteor
What is the key take-away from the figure below?
Models support the conclusion that human emissions are driving global warming.
This image from an Earth-based telescope shows smears of pink, blue, and purple, and colors. The tiny dots are stars. What primary astronomical object is depicted?
Nebula
An astronomer travels westward from Afghanistan toward Iran (in the northern hemisphere). Select which observations the astronomer will make about the north celestial pole (NCP) in their local sky.
None of the above.
Scientists have measured the minimum age of the solar system using radiometric dating which determines the time since the material was last melted and mixed with other materials. Which of the following would be best to determine the age of the solar system?
Primitive Meteorites
What does the graph below show us about what prevented the formation of a planet in the asteroid belt?
Repeated gravitational tugs from Jupiter at orbital resonances prevented material from coalescing to form a planet.
The image below represents an H-R Diagram. Which type(s) of object would you find in Region 6? (Select all that apply)
Super Giants
Why does the Doppler method only provide a measure of the minimum mass of a planet?
The Doppler shift tells only part of a host star's orbital speed (the part toward and away from the observer).
Consider the following statement: "Rocky asteroids are found primarily in the asteroid belt and Kuiper belt, while icy comets are found primarily in the Oort cloud." What's wrong with this statement?
The Kuiper belt contains icy comets, not rocky asteroids.
At which location(s) on Earth would you see no circumpolar stars (Select all that apply.)
The equator.
Astronomers observe the merger of two neutron stars in the Andromeda galaxy roughly 2.5 million light-years away Which of the following statements are true? (Select all that apply)
The merger occurred 2.5 million years ago.
Suppose that an exotic substance allowed us to make a balloon that floated above the Earth at the same altitude as the International Space Station. Which statement describes the weight of the balloon passengers as read on a scale below their feet.
The passengers' weights on the scale would be slightly less than on Earth.
Which of the following correctly describes the ecliptic?
The path the Sun takes every year across the celestial sphere each year.
The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?
The photo will seem to show only one star rather than two.
Which statement explains why the planets orbit the Sun in the same direction and in nearly the same plane as each other?
The planets formed from a disk of rotating gas, and their orbits therefore orbit as this gas did.
If a star has a smaller parallax angle when observed from Earth compared to another star, what does this indicate about the star?
The star is farther away from Earth.
What two pieces of information do we need about binary star systems in order to measure masses in binary star systems?
The stars' orbital periods and semi-major axes.
Suppose that an impact somehow showed the entire planet Earth in clouds, but everything else about the Earth's surface and atmosphere stayed the same. What would happen to Earth's average surface temperature?
The surface temperature would decrease because the Earth would be more reflective.
Why does Jupiter have three distinct layers of clouds?
The three layers represent clouds made of gases that condense at different temperatures.
Earth is farthest from the Sun in July and closest to the Sun in January. During which Northern Hemisphere season does Earth have the most total orbital energy?
The total orbital energy of Earth is the same in all seasons.
The Sirius is a star with a surface temperature of roughly 25,000K. A white dwarf stellar remnant has a surface temperature of 40,000 K but is MUCH smaller than Sirius. Which star is brighter?
The white dwarf is brighter.
Why do sunspots appear dark in pictures of the Sun?
They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere.
Some of the light that atomic hydrogen can emit have wavelengths of 21 cm (radio), 656 nm (red), 1.88 μm (infrared), 410 nm (violet), and 122 nm (ultraviolet). Arrange these from fastest speed to slowest speed in empty space.
They all travel at the same speed.
What is the primary reason why the majority of meteor particles do not reach the Earth's surface?
They are too small and are incinerated in the atmosphere.
Which of the following best describes why the smaller terrestrial worlds have cooler interiors than the larger ones?
They have relatively more surface area compared to their volumes.
Imagine that you are on the Moon while your friend experiences a total solar eclipse on Earth. What do you see?
You see a relatively small shadow on an otherwise full Earth.
Ancient riverbeds and other features show that Mars once had abundant liquid water on its surface. For this to have been true, early Mars must have had ________ than Mars today.
a much higher atmospheric pressure and much stronger greenhouse effect
How often do objects big enough to create craters like Meteor Crater impact Earth?
about once every ten thousand years
At which of the following lunar phase(s) are tides most pronounced (e.g., the highest high tides)?
both new and full Moons
Which of the following describes the process by which a heated material turns from a gas to a liquid or solid?
condensation
Suppose you live on the Moon. When people on Earth see the Moon in a crescent phase, what phase do you see for Earth?
gibbous Earth
According to models of planetary interiors, the differences in mass among the four Jovian planets (Jupiter, Saturn, Uranus, and Neptune) are due primarily to differences ...
in the amounts of material in the layers extending from the tops of their cores to their surfaces.
According to the universal law of gravitation, if the distance between two masses is decreased by a factor of 4, the gravitational force between those two masses...
increases by a factor of 16.
What kind of planet is most easily detected using the transit method?
large planets in edge-on orbits around small stars
The point along a planet's orbit where it is closest to the Sun is called the orbit's ____.
perihelion.
What is meant by Occam's Razor?
the idea that scientists should prefer the simpler of two models that agree equally well with observations
A planet is detected via the Doppler method. What does the time between peaks of the stellar velocity tell us?
the orbital period of the planet
Which of the following could be the Moon's phase if the Moon is rising at 3:00 AM?
waning crescent.
