M&A - EXAM 2 QUESTIONS AND CORRECT
ANSWERS.
Use Kepler's third law to find the planet's average distance (semimajor axis) from its star.
(Hint: Because the mass of 51 Pegasi is about the same as the mass of our Sun, you can use
Kepler's third law in its original form, . Be sure to convert the period into years before
using this equation.)
0.05 AU
The solar system has two types of planets, terrestrial and jovian. According to the nebular
theory, why did terrestrial planets form in the inner solar system and jovian planets in the
outer solar system?
Ices condensed only in the outer solar system, where some icy planetesimals grew large enough
to attract gas from the nebula, while only metal and rock condensed in the inner solar system,
making terrestrial planets.
Based on the nebular theory as it explains our own solar system, which of the following
should we expect to be true for other star systems?
-Other planetary systems should have the same two types of planets: terrestrial and jovian.
-Planetary systems should be common.
-Planetary systems should generally have all planets orbiting in nearly the same plane.
-Jovian planets always form farther from their star than terrestrial planets.
Based on what we know about our own solar system, the discovery of hot Jupiters came as
a surprise to scientists because these planets are __________.
so close to their stars
Our modern theory of solar system formation—the nebular theory—successfully accounts
for all the major features of our own solar system. However, when the first hot Jupiters
were discovered, their existence seemed inconsistent with the nebular theory because this
theory predicts that __________.
jovian planets can form only in the cold, outer regions of a solar system
, Because the discovery of hot Jupiters surprised scientists, they had to consider why the
nebular theory had not predicted this discovery in advance. Which statement below does
not describe a scientifically reasonable explanation for why the nebular theory failed to
predict the existence of the hot Jupiters?
The nebular theory applies only to our solar system; other solar systems need their own
formation theories.
Scientists seriously considered all of the scientifically reasonable possibilities in Part C.
Today, most scientists favor the hypothesis that hot Jupiters formed in their outer solar
systems and then migrated inward. Why did this hypothesis gain favor over the
alternatives?
Computer models that simulate planetary formation show that interactions between young
planets and the surrounding disk of gas and dust can cause planetary migration.
Assume that the migration hypothesis is the correct explanation for the hot Jupiters. In
that case, the revised nebular theory looks just like the old theory, except that it now allows
for the possibility of migration. Which of the following statements are consistent with this
revised theory?
-Terrestrial planets always form in the warm, inner regions of their star system.
-Jovian planets always form in the cold, outer regions of their star system.
-Jovian planets can migrate inward and disrupt the orbits of terrestrial planets.
Two hypothetical discoveries in Part A deal with moons that, like Earth's moon, are
relatively large compared to their planets. Which of the following best explains why finding
1 planet with such a moon is consistent with the nebular theory, while finding 6 planets
with such moons is not consistent?
Unusually large moons form in giant impacts, which are relatively rare events.
Consider the hypothetical discovery from Part A reading: "A star's 5 terrestrial planets
orbit in the opposite direction of its 3 jovian planets." This discovery would be inconsistent
with the nebular theory because the theory holds that __________.
all the planets formed in a rotating, disk-shaped nebula
ANSWERS.
Use Kepler's third law to find the planet's average distance (semimajor axis) from its star.
(Hint: Because the mass of 51 Pegasi is about the same as the mass of our Sun, you can use
Kepler's third law in its original form, . Be sure to convert the period into years before
using this equation.)
0.05 AU
The solar system has two types of planets, terrestrial and jovian. According to the nebular
theory, why did terrestrial planets form in the inner solar system and jovian planets in the
outer solar system?
Ices condensed only in the outer solar system, where some icy planetesimals grew large enough
to attract gas from the nebula, while only metal and rock condensed in the inner solar system,
making terrestrial planets.
Based on the nebular theory as it explains our own solar system, which of the following
should we expect to be true for other star systems?
-Other planetary systems should have the same two types of planets: terrestrial and jovian.
-Planetary systems should be common.
-Planetary systems should generally have all planets orbiting in nearly the same plane.
-Jovian planets always form farther from their star than terrestrial planets.
Based on what we know about our own solar system, the discovery of hot Jupiters came as
a surprise to scientists because these planets are __________.
so close to their stars
Our modern theory of solar system formation—the nebular theory—successfully accounts
for all the major features of our own solar system. However, when the first hot Jupiters
were discovered, their existence seemed inconsistent with the nebular theory because this
theory predicts that __________.
jovian planets can form only in the cold, outer regions of a solar system
, Because the discovery of hot Jupiters surprised scientists, they had to consider why the
nebular theory had not predicted this discovery in advance. Which statement below does
not describe a scientifically reasonable explanation for why the nebular theory failed to
predict the existence of the hot Jupiters?
The nebular theory applies only to our solar system; other solar systems need their own
formation theories.
Scientists seriously considered all of the scientifically reasonable possibilities in Part C.
Today, most scientists favor the hypothesis that hot Jupiters formed in their outer solar
systems and then migrated inward. Why did this hypothesis gain favor over the
alternatives?
Computer models that simulate planetary formation show that interactions between young
planets and the surrounding disk of gas and dust can cause planetary migration.
Assume that the migration hypothesis is the correct explanation for the hot Jupiters. In
that case, the revised nebular theory looks just like the old theory, except that it now allows
for the possibility of migration. Which of the following statements are consistent with this
revised theory?
-Terrestrial planets always form in the warm, inner regions of their star system.
-Jovian planets always form in the cold, outer regions of their star system.
-Jovian planets can migrate inward and disrupt the orbits of terrestrial planets.
Two hypothetical discoveries in Part A deal with moons that, like Earth's moon, are
relatively large compared to their planets. Which of the following best explains why finding
1 planet with such a moon is consistent with the nebular theory, while finding 6 planets
with such moons is not consistent?
Unusually large moons form in giant impacts, which are relatively rare events.
Consider the hypothetical discovery from Part A reading: "A star's 5 terrestrial planets
orbit in the opposite direction of its 3 jovian planets." This discovery would be inconsistent
with the nebular theory because the theory holds that __________.
all the planets formed in a rotating, disk-shaped nebula
