ASTR Midterm 3 Review #2

28. If the sun's surface cooled, how would its appearance change? A) It would appear more red. B) It would appear more blue. C) It would become bright white. D) It would stay the same.

A) It would appear more red.

32. What evidence suggests that the Milky Way contains dark matter? A) We observe clouds of atomic hydrogen far from the galactic center orbiting the galaxy at unexpectedly high speeds, higher speeds than they would have if they felt only the gravitational attraction from objects that we can see. B) We see many lanes of dark material blocking out the light of stars behind them along the band of the Milky Way. C) We see many dark voids between the stars in the halo of the Milky Way. D) When we observe in different wavelengths, such as infrared or radio, we see objects that don't appear in visible-light observations. E) When we look at the galactic center, we are able to observe a large black hole that is composed of dark matter

A) We observe clouds of atomic hydrogen far from the galactic center orbiting the galaxy at unexpectedly high speeds, higher speeds than they would have if they felt only the gravitational attraction from objects that we can see.

21. Energy to support an origin of life in a Europan ocean would probably come from A) deep-sea volcanic vents B) sunlight filtering through the ice C) meteoroid impacts on the surface D) heat generated from Jupiter's magnetic field

A) deep-sea volcanic vents

11. Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission? A) iron B) hydrogen C) oxygen D) silicon

A) iron

29. Many of the known extrasolar planets orbit their stars A) more closely than Mercury orbits the Sun B) at about the same distance as the Earth orbits the Sun C) at about the same distance as the planet Jupiter orbits the Sun D) much further than the distance the planet Jupiter orbits the Sun

A) more closely than Mercury orbits the Sun

29. When the Sun was younger, how did its habitable zone compare with its habitable zone today? A) narrower and closer to the Sun B) narrower and farther from the Sun C) wider and closer to the Sun D) wider and farther from the Sun

A) narrower and closer to the Sun

25. If Venus had the same atmosphere as the Earth, it would A) only be slightly warmer B) be at exactly the same temperature C) be very much warmer D) be slightly colder

A) only be slightly warmer

7. The minimum size that makes it possible for a planetary surface to remain habitable over long time periods is a size that allows A) plate tectonics to be present B) a magnetic field to be present C) an atmosphere to be present D) hot spot volcanism to be present

A) plate tectonics to be present

17. Which of the following sequences correctly describes the stages of life for a low-mass star? A) protostar, main-sequence, red giant, white dwarf B) red giant, protostar, main-sequence, white dwarf C) white dwarf, main-sequence, red giant, protostar D) protostar, red giant, main-sequence, white dwarf E) protostar, main-sequence, white dwarf, red giant

A) protostar, main-sequence, red giant, white dwarf

37. Stars of spectral type A and F are considered ________. A) reasonably likely to have habitable planets, but much less likely to have planets with complex plant- or animal-like life B) reasonably likely to have Earth-like planets with complex plant- and animal-like life C) unlikely to have planets of any kind D) unlikely to have habitable planets

A) reasonably likely to have habitable planets, but much less likely to have planets with complex plant- or animal-like life

17. Which of the following methods has been the LEAST successful in detecting extrasolar planets around other star systems? A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky B) detection of Doppler shifts in the spectra of the parent stars C) detection of brightness changes in a star as a planet passes in front of it D) detection of reflected starlight

A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky

12. The presence of elements heavier than helium in stars is very important because A) they provide the raw materials for the formation of planets and life B) without them they could not form C) they help stabilize their interiors D) they are responsible for the fusion reactions at their centers

A) they provide the raw materials for the formation of planets and life

38. Is Europa in the Sun's habitable zone? A) It is if it really has a subsurface ocean, but otherwise is not. B) No C) Yes

B) No

17. Which of the following is a moon of Neptune? A) Titan B) Triton C) Europa D) Ganymede

B) Triton

18. Compared to young stars, very old stars have A) exactly the same chemical composition B) a lower proportion of elements heavier than helium C) a higher proportion of elements heavier than helium D) no elements heavier than helium at all

B) a lower proportion of elements heavier than helium

22. The wavelengths of radiation from a star that is moving toward us A) can be longer or shorter depending on the distance to the star B) are shorter than if the star were not moving C) are longer than if the star were not moving D) are the same as if the star were not moving

B) are shorter than if the star were not moving

30. Why does the Sun brighten with time? A) as time progresses, helium starts to fuse in the core, in addition to hydrogen, leading to an increase in brightness B) as hydrogen is converted into helium in the core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by shrinking and heating up C) as time progresses, more and more heat is trapped inside the core, leading to an increase in brightness D) as hydrogen is converted into helium in the core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by expanding and cooling

B) as hydrogen is converted into helium in the core, the number of hydrogen nuclei decreases, decreasing the fusion rate. To maintain the balance with gravity pressing inward, the core compensates by shrinking and heating up

37. In most extrasolar planetary systems the center of mass is likely to be located A) midway between the star and its most massive planet B) close to the center of the parent star C) exactly at the center of the parent star D) close to the center of the most massive planet

B) close to the center of the parent star

38. Which of the following methods has been the MOST successful in detecting extrasolar planets around other star systems? A) regular changes in the positions of the parent stars with respect to more distant stars as they move across the sky B) detection of brightness changes in a star as a planet passes in front of it C) detection of Doppler shifts in the spectra of the parent stars D) detection of reflected starlight

B) detection of brightness changes in a star as a planet passes in front of it

18. Jovian moons are typically made of A) solid ice B) ice and rock C) rock and iron D) solid rock

B) ice and rock

23. Over time, as they age, the habitable zone of stars like our Sun A) move inward B) move outward C) remain the same D) suddenly disappear

B) move outward

8. Compared to the average surface temperature on the surface of the Earth, the average surface temperature on the surface of Mars is A) about the same B) much lower C) just slightly lower D) much higher

B) much lower

33. The current concentration of carbon dioxide in Earth's atmosphere is ________. A) higher than it has been during the past century, but lower than at many other times during past millennia B) significantly higher than it has been for at least several hundred thousand years C) higher than it has ever been in Earth's history D) rising, but still about average for the past few hundred thousand years

B) significantly higher than it has been for at least several hundred thousand years

9. Sunspots are cooler than the surrounding gas in the photosphere because A) they are regions where convection carries cooler material downward. B) strong magnetic fields slow convection and prevent hot plasma from entering the region. C) magnetic fields trap ionized gases that absorb light. D) there is less fusion occurring there. E) magnetic fields lift material from the sunspot and quickly cool the material.

B) strong magnetic fields slow convection and prevent hot plasma from entering the region.

3. Which of the following statements regarding the determination of surface habitability and subsurface habitability of a planet is correct? A) both surface and subsurface habitability can be determined only from robotic space probes B) surface habitability can be determined remotely by studying reflected starlight from a planet, while determining subsurface habitability would require a robotic space probe C) both surface and subsurface habitability can be determined by analyzing reflected starlight D) subsurface habitability can be determined remotely by studying reflected starlight from a planet, while determining surface habitability would require a robotic space probe

B) surface habitability can be determined remotely by studying reflected starlight from a planet, while determining subsurface habitability would require a robotic space probe

39. A white dwarf is A) the exposed core of a dead star, supported by neutron degeneracy pressure. B) the exposed core of a dead star, supported by electron degeneracy pressure. C) a hot but very small main sequence star with a mass of less than 1.4 solar masses. D) a cool and very small main sequence star with a mass of less than 1.4 of a solar masses. E) the name for the singularity at the center of a black hole.

B) the exposed core of a dead star, supported by electron degeneracy pressure.

23. Apart from its distance from its parent star, what is the next most important factor that determines a planet's habitability? A) whether it has a large moon B) the size of the planet C) the chemical composition of its atmosphere D) the chemical composition of its surface

B) the size of the planet

2. Europa is located outside the Sun's habitable zone and yet may be habitable. How can this be? A) Europa's subsurface ocean contains lots of minerals that allow water to remain liquid at much lower temperatures B) Europa is continually being hit by comets and asteroids which keeps water beneath its surface liquid C) Europa is tidally heated, allowing liquid water to exist beneath its icy surface D) Europa is large enough to have appreciable heat trapped inside it to keep water beneath the surface liquid

C) Europa is tidally heated, allowing liquid water to exist beneath its icy surface

32. Venus probably once had as much water (or water vapor) as Earth. What do we think happened to all this water? A) It is hidden in subsurface reservoirs. B) It exists as water vapor in Venus's clouds. C) The water molecules were destroyed, and the hydrogen atoms escaped to space. D) It became locked into rocks as hydrated minerals.

C) The water molecules were destroyed, and the hydrogen atoms escaped to space.

20. When Mercury or Venus passes in front of the disk of the Sun, we call this A) an eclipse B) a shadow event C) a transit D) an occultation

C) a transit

33. What is the CNO cycle? A) the process by which helium is fused into carbon, nitrogen, and oxygen B) the process by which carbon is fused into nitrogen and oxygen C) a type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts D) the period of a massive star's life when carbon, nitrogen, and oxygen are fusing in different shells outside the core E) the period of a low-mass star's life when it can no longer fuse carbon, nitrogen, and oxygen in its core

C) a type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts

35. Solar-type stars in our galaxy are A) very common, making up about 50% of the total B) very rare (less than 1%) C) fairly common (several percent) D) the most common type of stars in our galaxy (75% or more)

C) fairly common (several percent)

27. The case of Mars tells us that which of the following is a critical factor in determining surface habitability? A) levels of geological activity B) distance from the Sun C) planetary size D) the presence of a magnetic field

C) planetary size

22. The Moon is in the habitable zone of the Sun at the same distance as the Earth but is not habitable. How can this be? A) the Moon did have water on its surface in the past, but it was destroyed by high-energy particles from the Sun B) the Moon has never had water on its surface at any time C) the Moon is too small to retain an atmosphere necessary for liquid water to be stable D) the Moon did have water on its surface in the past, but it was blasted off the surface by impacts

C) the Moon is too small to retain an atmosphere necessary for liquid water to be stable

38. Based on the observed amount of deuterium in the universe, we can conclude that A) ordinary (baryonic) matter makes 75 percent of the mass of the universe. B) neutrons outnumber protons 7 to 1 in the universe. C) the density of ordinary (baryonic) matter is about 5 percent of the critical density. D) most of the deuterium that was created during the era of nucleosynthesis has since been destroyed. E) we live in a critical-density universe.

C) the density of ordinary (baryonic) matter is about 5 percent of the critical density.

6. The public debate about Martian canals was not resolved until A) many scientists were unable to reproduce Percival Lowell's sketches of Martian canals B) the governing body of astronomy, the International Astronomical Union made an official statement on the matter C) the first spacecraft flew past Mars in 1965 D) the first spacecraft landed on Mars in 1976

C) the first spacecraft flew past Mars in 1965

34. Based on its surface temperature of 6,000 K, most photons that leave the Sun's surface lie in which region of the electromagnetic spectrum? A) microwave B) infrared C) visible D) ultraviolet E) X-ray

C) visible

25. A star more luminous than our Sun will have a habitable zone that is A) narrower and farther from the star than the habitable zone of the Sun B) narrower and closer to the star than the habitable zone of the Sun C) wider and farther from the star than the habitable zone of the Sun D) wider and closer to the star than the habitable zone of the Sun

C) wider and farther from the star than the habitable zone of the Sun 6. A star less luminous than our Sun will have a habitable zone that is A) narrower and closer to the star than the habitable zone of the Sun

13. Martian volcanoes are larger than volcanoes on Earth because A) Mars's weaker gravity makes it easier for tall structures to be built up. B) the lack of plate tectonics on Mars means that mantle plumes remain stationary relative to the surface, building up huge, single mountains. C) Mars has more internal heat than the Earth so volcanoes naturally grow to much larger sizes D) Both A and B

D) Both A and B

40. What role does an atmosphere play in surface habitability? A) it exerts a pressure which allows liquid water to be stable B) it protects the surface against harmful solar radiation C) it helps generate a protective magnetic field D) Both A and B

D) Both A and B C --> plate tectonics!

35. Suppose you are using the Doppler technique to look for planets around another star. What must you do? A) Compare the brightness of the star over a period of many months or years. B) Carefully examine a single spectrum of the star. C) Carefully examine a single spectrum of an orbiting planet. D) Compare many spectra of the star taken over a period of many months or years. E) Compare many spectra of an orbiting planet taken over a period of many months or years.

D) Compare many spectra of the star taken over a period of many months or years. Planets cause stars to wobble

3. What observations characterize solar maximum? A) The Sun becomes much brighter. B) The Sun emits light of longer average wavelength. C) The Sun rotates faster at its poles. D) There are many sunspots visible on the surface of the Sun. E) all of the above

D) There are many sunspots visible on the surface of the Sun.

3. Which of the following is an advantage that liquid water has as a biological solvent compared to other alternatives? A) when it freezes it becomes less dense B) it is a liquid over a wide temperature range and remains liquid at higher temperatures C) it is able to dissolve many things D) all of these are advantages

D) all of these are advantages

27. The results of statistical studies of the exoplanet systems discovered to date suggest that A) planets are common B) small planets outnumber large plates by a significant margin C) Earth-size planets are very common D) all of these are true

D) all of these are true

39. The wavelengths of radiation from a star that is moving away from us A) can be longer or shorter depending on the distance to the star B) are shorter than if the star were not moving C) are the same as if the star were not moving D) are longer than if the star were not moving

D) are longer than if the star were not moving

23. Why does the Doppler shift method of detecting extrasolar planets only give us the minimum mass of a planet? A) because we don't necessarily know the density of the planet B) because we don't necessarily know the diameter (size) of the planet C) because we don't necessarily know the mass of the parent star very D) because we don't necessarily know the angle the planet's orbit makes with our line of sight

D) because we don't necessarily know the angle the planet's orbit makes with our line of sight

37. The figure on the right shows the abundance of elements in the galaxy relative to hydrogen. What is the general trend in elemental abundance? A) Elements with more protons are less abundant. B) Elements with an odd number of protons are less abundant than neighboring elements. C) Elements with an even number of protons are less abundant than neighboring elements. D) both A and B E) both A and C

D) both A and B

14. The ancient water erosion features on the surface of Mars suggest that the planet must have had a much A) warmer, thinner atmosphere in the past B) cooler, thicker atmosphere in the past C) cooler, thinner atmosphere in the past D) warmer, thicker atmosphere in the past

D) warmer, thicker atmosphere in the past

29. Which of the following statements about spectral types of stars is true? A) The spectral type of a star can be used to determine its surface temperature. B) The spectral type of a star can be used to determine its color. C) A star with spectral type A is cooler than a star with spectral type B. D) A star with spectral type F2 is hotter than a star with spectral type F3. E) All of the above are true.

E) All of the above are true.

10. At the center of the Sun, nuclear fusion converts hydrogen into A) hydrogen compounds such as methane. B) molecular hydrogen. C) radiation and elements such as carbon and nitrogen. D) radioactive elements such as uranium and plutonium. E) helium, gamma rays, and neutrinos.

E) helium, gamma rays, and neutrinos.

10. Which of the following sequences correctly describes the stages of life for a low-mass star? A) red giant, protostar, main-sequence, white dwarf B) white dwarf, main-sequence, red giant, protostar C) protostar, red giant, main-sequence, white dwarf D) protostar, main-sequence, white dwarf, red giant E) protostar, main-sequence, red giant, white dwarf

E) protostar, main-sequence, red giant, white dwarf

4. A star's luminosity is the A) apparent brightness of the star in our sky. B) surface temperature of the star. C) lifetime of the star. D) total amount of energy that the star will radiate over its entire lifetime. E) total amount of energy that the star radiates each second.

E) total amount of energy that the star radiates each second.

41. Life in the subsurface ocean of Europa will most likely consist of plants on the ocean floor.

False

41. Sunlight is probably the most likely source of energy for life in the atmospheres of Jovian planets

False

43. The phase of matter in the Sun is a mixture of plasma and gas.

False

44. The Mars Reconnaissance Orbiter has been measuring the escape of gases from the Martian atmosphere

False

49. As the average surface temperature of the Earth rises, the Southern hemisphere of the Earth is warming more rapidly than the Northern hemisphere because the Southern hemisphere contains more landmass which more readily absorbs solar radiation.

False

46. Titan is the largest moon in the solar system.

False - Ganymede is

47. A carbon dioxide concentration of 400 parts per million (ppm) means that carbon dioxide represents about 4% of Earth's atmosphere.***

False: 400 parts per million means 400 divided by 1 million, which gives 0.0004, which is 0.04%, not 4%.

47. If a star has an extrasolar planet, the amplitude of its radial velocity curve is related to the planet's mass.

TRUE

42. Most of the detailed information about the planets in our solar system comes from robotic spacecraft.

True

43. Even though the Martian atmosphere is composed almost completely of the greenhouse gas carbon dioxide, its surface is much colder than the Earth because its atmosphere is much thinner.

True

45. The most distant stars we can currently measure stellar parallax for are approximately 1000 parsecs away.

True

46. On the main sequence, stars obtain their energy by converting hydrogen to helium.

True

48. When the Sun runs out of nuclear fuel and expands to become a red giant, the Earth will experience a runaway greenhouse effect followed by the total loss of its atmosphere.

True

42. The Sun will most likely engulf Mercury, Venus, and the Earth when it becomes a red giant.

True: This is not referring to the habitable zone, but the fact that at the end of its life, when the Sun becomes a red giant, it will grow so large that it will fill the inner solar system, eating up Mercury, Venus, and most probably Earth as well.