Astronomy- Chapter 7

As the solar nebula contracts due to gravitation, the cloud A) spins faster. B) expands. C) becomes more spherical in shape. D) changes direction of motion. E) begins to cool.

The Kuiper Belt is found where in the solar system? A) Among the orbits of the terrestrial planets B) Beyond the orbit of Neptune C) Between the orbits of Mars and Jupiter D) Between the orbits of Jupiter and Uranus E) Sixty degrees ahead or behind Jupiter

Which of these is NOT a characteristic of the solar nebula theory? A) The ecliptic is the equator for the Sun. B) All the planets should follow the ecliptic plane. C) All the planets should orbit the Sun counterclockwise. D) Larger planets should form closer to their star, where there is more debris. E) Planets should rotate counterclockwise as well.

What might have made the original solar nebula begin to contract? A) The Big Bang B) The formation of our arm of the Milky Way C) The shock wave from a nearby exploding star D) Interstellar magnetism generated by pulsars E) The large amount of angular momentum in the nebula

A successful theory of the formation of the solar system must explain A) that all planets rotate in a prograde sense. B) that all planets have elliptical orbits with high eccentricities. C) the existence of the asteroid belt between Jupiter and Neptune. D) that the inner planets have more hydrogen and helium in their atmospheres than do the outer planets. E) all observed properties of the solar system.

Planetary orbits A) are evenly spaced throughout the solar system. B) are highly inclined to the ecliptic. C) are almost circular, with low eccentricities. D) have the Sun at their exact center. E) are spaced more closely together as they get further from the Sun.

What happens when a solar nebula contracts? A) It flattens out. B) It spins faster. C) It heats up. D) All of the above E) None of the above

In light of modern solar system theory, why do the orbits of the planets all lie in the same plane? A) The Sun's gravity forced them into these orbits. B) The angular momentum of the solar system was kept to a minimum this way. C) The early solar nebula flattened into a disk. D) Comets would have wiped out any not in this protected plane. E) This happened purely by chance.

Conservation of angular momentum means that a spinning body tends to A) fly apart. B) slow down. C) wobble into an eccentric orbit. D) gravitationally collapse. E) keep spinning.

Dust is an important part of the nebular theory of solar system formation because dust is needed to explain A) how the inner planets came to be rocky bodies. B) how the outer planets came to be gaseous bodies. C) how the initial cloud cooled enough to collapse. D) how the initial cloud heated as it contracted. E) why the icy bodies are located so far from the Sun.

As a rotating gas cloud contracts, it spins A)faster due to an increase in angular momentum. B) slower due to a decrease in angular momentum. C) at a constant rate. D) faster due to conservation of angular momentum. E) slower due to conservation of angular momentum

As the solar nebula contracts it A) flattens out into the ecliptic plane around the Sun's poles. B) spins faster due to conservation of angular momentum. C) cools due to condensation. D) loses angular momentum. E) reverses it direction of rotation.

What is the role of irregularities in the solar system in terms of theories of its origin? A) They are too minor to play a role; astronomers ignore them. B) They introduce a need for flexibility in theories of the solar system's origin. C) Theories of the solar system are entirely based on the many irregularities found among the planets and moons. D) The solar system has no irregularities; it is perfectly regular and orderly. E) The solar system is chaotic, with irregularities the rule.

Which objects in the solar system have been least modified since the formation of the solar system? A) Asteroids B) Kuiper Belt objects C) Meteoroids D) Terrestrial planets E) Jovian moons

The jovian planets A) all lie less than 5 AU from the Sun. B) all have rings around their equators. C) all spin slower than the Earth. D) have satellite systems with less than 4 moons. E) are all much more dense than any of the terrestrials planets.

What factor caused different planets to form out of different types of material? A) The angular momentum of the forming planet; faster rotating planets lost the lightest elements. B) The quantity of dust particles in the solar nebula; more dust caused some planets to contain heavier elements. C) The variation in temperature throughout the solar nebula; the higher the temperature, the lower the percentage of light elements in the forming planet. D) The angular momentum of the solar nebula pushed the heavy elements towards the outer regions of the nebula. E) The innate variation of chemical composition of the original nebula; the outer parts of the nebula contained a greater abundance of heavy elements.

What is the process of accretion? A) The separation of materials in a protoplanet by density, with dense material in core B) Growth of an object by the accumulation of matter C) The breakup of large objects by violent collisions with other similar-sized objects D) The period of time during which the Sun swept away all the excess material in the solar nebula E) The process by which the solar nebula became heated during its collapse

In the conventional scenario, during phase of planet formation caused the jovian planets to form? A) Core-accretion B) Fragmentation C) Differentiation D) Collision E) Condensation

An alternative to the core-accretion theory that explains the formation of the jovian planets is the A) differentiation theory. B) collision theory. C) gravitational instability theory. D) Big Bang theory. E) nebular contraction theory.

The moons of the jovian planets formed by which two processes? A) Accretion and collisions B) Capture and collisions C) Collisions and differentiation D) Accretion and capture E) Differentiation and capture

As a result of the ejection of planetesimals into the Oort Cloud, simulations indicate that Uranus and Neptune moved A) closer to the Sun. B) further from the Sun. C) along their orbits at a different rate. D) from the inner solar system to the outer solar system. E) from the outer solar system to the inner solar system.

According to the planetary migration model, the jovian planets are thought to have formed A) in the orbit where they are now. B) further from the Sun than they are now. C) in another solar system. D) closer to the Sun than they are now. E) none of the above.

The Oort Cloud is believed to have been formed by A) planetesimals that were flung far from the Sun in gravitational encounters with the jovian planets. B) icy bodies formed between stars that have been captured by our solar system's gravity. C) moons that escaped from the jovian planets. D) debris from an icy planet that broke apart early in the solar system's history. E) debris from impacts of planetesimals, asteroids and comets with the jovian planets.

The Kuiper Belt is A) another name for the Asteroid Belt. B) a band of icy planetesimals found beyond Neptune's orbit. C) where all comets come from. D) the name given to icy bodies found between Jupiter and Saturn. E) the name given to icy bodies found between Mars and Jupiter.

When was the first confirmed exoplanet discovered? A) Shortly after the invention of the telescope, in the early 1600s B) In prehistoric times C) Around 350 BC, by the Ancient Greeks D) Early in the 21st century E) Near the end of the 20th century

The Doppler radial velocity technique works best for A) planets whose orbits are along are line of sight. B) planets whose orbits are perpendicular to our line of sight. C) planets whose orbits are nearly circular. D) planets whose orbits are very eccentric.

When looking for the "Doppler Wobble" (radial velocity changes detected due to Doppler shifts), which mass combination is most likely to be detected? A) High mass star, high mass planet B) High mass star, low mass planet C) Low mass star, high mass planet D) Low mass star, low mass planet E) A high mass planet; the mass of the star is irrelevant.

The Kepler mission uses which technique to detect planet candidates? A) Radial velocity measurements B) Direct imaging C) Measurements of transverse motion D) Planetary transits

Which statement about extrasolar planets found to date is TRUE? A) All are terrestrials, comparable in size to Earth. B) Few are found by Doppler shifts of their stars, due to their gravity. C) All lie more than 2 AU from their star. D) Most have orbital periods of more than a year. E) Some are so close to their stars that their periods are just a few days.

Which molecule has not yet been detected in the atmospheres of exoplanets? A) Methane B) Carbon dioxide C) Oxygen D) Water

Planets found in the habitable zone of other stars A) are all rocky planets, like the terrestrial planets in our solar system. B) are all jovian planets. C) include some Earths and super-Earths. D) include hot Jupiters. E) have been demonstrated to be barren of all life.

Most of first extrasolar planets found were detected by A) noting the drop in the star's light as the planet transits its disk. B) imaging them with the HST in the infrared, where they are easier to stop. C) noting the Doppler shifts of the star as the planet orbits it from side to side. D) receiving radio transmissions from them, much like Jupiter emits. E) detecting the oxygen in their atmospheres spectroscopically.

Super-earths are A) planets that are most earthlike, likely to harbor life. B) planets that are a few times the mass of the Earth. C) planets that have earthlike masses, but orbit much closer to their star than the Earth does to the Sun. D) any rocky (or terrestrial) planet. E) Earth-mass planets that are much lower in density than the Earth, giving them larger radii.

Most extrasolar Neptunes and Jupiters found to date have A) orbits very close to their parent stars, making them hot Neptunes and hot Jupiters. B) orbits that are more eccentric than those of planets in our solar system, with eccentricities greater than 0.1 C) orbits that are less eccentric than those of planets in our solar system, with eccentricities less than 0.01. D) much larger orbits than the jovian planets in our solar system.

When we are lucky enough to see an extra-solar planet transit its star A) It will cause the star to vanish for several hours. B) We can by the drop in light find the planet's size, mass, and density. C) We can determine what elements are in its atmosphere. D) We can determine its shape. E) We can be certain it is a terrestrial, not a jovian.

In the process of planetary formation, when would the inward migration of Jupiters have been most likely? A) Shortly after all of the planets had finished forming B) Just after the system was cleared of the remaining gas C) Before these planets had grown to full size D) After these planets had reached full size, but before terrestrial planets had finished forming E) At least hundreds of millions of years after planetary formation ended