PHYS 1160 INTRODUCTION TO ASTRONOMY
FINAL PAPER 2026 QUESTIONS WITH
ANSWERS GRADED A+
◉ Which planet has the highest average surface temperature, and why?
Answer: Venus, because of its dense carbon dioxide atmosphere
◉ Which of the following observations indicates that Mars had a
warmer, thicker atmosphere in the past? Answer: There are dried-up
riverbeds on Mars.
◉ Which of the following is the only characteristic Pluto shares with the
outer planets? Answer: It has multiple moons.
◉ In what part of the solar system is Pluto found? Answer: the Kuiper
belt
◉ Planetary orbits in our solar system are: Answer: fairly circular and in
the same plane.
,◉ Why did the solar nebula flatten into a disk? Answer: It flattened as a
natural consequence of collisions between particles in the nebula,
changing random motions into more orderly ones.
◉ What percentage of the solar nebula's mass consisted of hydrogen and
helium gases? Answer: 98 percent
◉ Which of the following did not occur during the collapse of the solar
nebula? Answer: concentrating denser materials nearer the Sun
◉ Which of the following lists the composition of the solar nebula from
highest to lowest percentage of mass? Answer: light gases (H, He),
hydrogen compounds (H2O, CH4, NH3), rocks, metals
◉ According to our theory of solar system formation, why do we find
some exceptions to the general rules and patterns of the planets?
Answer: Most of the exceptions are the result of giant impacts or close
gravitational encounters.
◉ Observations of young stars (as well as theory) tell us that when the
Sun was young, the solar wind Answer: -was stronger than it is today.
◉ In light of what you've learned about the formation of our own solar
system, decide whether the discovery should be considered reasonable
or surprising. Answer: -Surprising. In the process of nebular capture the
,formation of large number moons at a jovian planet is more likely that at
a terrestrial planet.
◉ What do meteorites reveal about the solar system? Answer: They
reveal that the age of the solar system is approximately 4.6 billion years.
◉ Every 4.5 billion years, half of the atoms in a sample of uranium-238
will undergo radioactive decay and become atoms of lead-206. Suppose
you lived in another planetary system around a faraway star and found a
meteorite that was originally made of uranium-238, but is now one-
quarter uranium-238 and three-quarters lead-206. What would be your
best estimate of that planetary system's age? Answer: 9 billion years
◉ The age of the solar system can be established by radiometric dating
of Answer: the oldest meteorites.
◉ Suppose you find a rock that contains some potassium-40 (half-life of
1.25 billion years). You measure the amount and determine that there are
5 grams of potassium-40 in the rock. By measuring the amount of its
decay product (argon-40) present in the rock, you realize that there must
have been 40 grams of potassium-40 when the rock solidified. How old
is the rock? Answer: 3.75 billion years
◉ About how old is the solar system? Answer: 4.5 billion years
, ◉ Under what circumstances can differentiation occur in a planet?
Answer: The planet must have a molten interior.
◉ The lithosphere of a planet is the layer that consists of Answer: the
rigid rocky material of the crust and uppermost portion of the mantle.
◉ The terrestrial planet cores contain mostly metal because Answer:
metals sank to the center during a time when the interiors were molten
throughout.
◉ What process initially caused the terrestrial planets to be hot enough
to be entirely molten? Answer: accretion
◉ What are the circumstances under which convection can occur in a
substance? Answer: when the substance is strongly heated from
underneath
◉ Why does the interior of a large planet take longer to cool than the
interior of a smaller planet? Answer: Small planets have a larger surface
area-to-volume ratio than larger planets.
◉ Which of the terrestrial worlds has the strongest magnetic field?
Answer: Earth
FINAL PAPER 2026 QUESTIONS WITH
ANSWERS GRADED A+
◉ Which planet has the highest average surface temperature, and why?
Answer: Venus, because of its dense carbon dioxide atmosphere
◉ Which of the following observations indicates that Mars had a
warmer, thicker atmosphere in the past? Answer: There are dried-up
riverbeds on Mars.
◉ Which of the following is the only characteristic Pluto shares with the
outer planets? Answer: It has multiple moons.
◉ In what part of the solar system is Pluto found? Answer: the Kuiper
belt
◉ Planetary orbits in our solar system are: Answer: fairly circular and in
the same plane.
,◉ Why did the solar nebula flatten into a disk? Answer: It flattened as a
natural consequence of collisions between particles in the nebula,
changing random motions into more orderly ones.
◉ What percentage of the solar nebula's mass consisted of hydrogen and
helium gases? Answer: 98 percent
◉ Which of the following did not occur during the collapse of the solar
nebula? Answer: concentrating denser materials nearer the Sun
◉ Which of the following lists the composition of the solar nebula from
highest to lowest percentage of mass? Answer: light gases (H, He),
hydrogen compounds (H2O, CH4, NH3), rocks, metals
◉ According to our theory of solar system formation, why do we find
some exceptions to the general rules and patterns of the planets?
Answer: Most of the exceptions are the result of giant impacts or close
gravitational encounters.
◉ Observations of young stars (as well as theory) tell us that when the
Sun was young, the solar wind Answer: -was stronger than it is today.
◉ In light of what you've learned about the formation of our own solar
system, decide whether the discovery should be considered reasonable
or surprising. Answer: -Surprising. In the process of nebular capture the
,formation of large number moons at a jovian planet is more likely that at
a terrestrial planet.
◉ What do meteorites reveal about the solar system? Answer: They
reveal that the age of the solar system is approximately 4.6 billion years.
◉ Every 4.5 billion years, half of the atoms in a sample of uranium-238
will undergo radioactive decay and become atoms of lead-206. Suppose
you lived in another planetary system around a faraway star and found a
meteorite that was originally made of uranium-238, but is now one-
quarter uranium-238 and three-quarters lead-206. What would be your
best estimate of that planetary system's age? Answer: 9 billion years
◉ The age of the solar system can be established by radiometric dating
of Answer: the oldest meteorites.
◉ Suppose you find a rock that contains some potassium-40 (half-life of
1.25 billion years). You measure the amount and determine that there are
5 grams of potassium-40 in the rock. By measuring the amount of its
decay product (argon-40) present in the rock, you realize that there must
have been 40 grams of potassium-40 when the rock solidified. How old
is the rock? Answer: 3.75 billion years
◉ About how old is the solar system? Answer: 4.5 billion years
, ◉ Under what circumstances can differentiation occur in a planet?
Answer: The planet must have a molten interior.
◉ The lithosphere of a planet is the layer that consists of Answer: the
rigid rocky material of the crust and uppermost portion of the mantle.
◉ The terrestrial planet cores contain mostly metal because Answer:
metals sank to the center during a time when the interiors were molten
throughout.
◉ What process initially caused the terrestrial planets to be hot enough
to be entirely molten? Answer: accretion
◉ What are the circumstances under which convection can occur in a
substance? Answer: when the substance is strongly heated from
underneath
◉ Why does the interior of a large planet take longer to cool than the
interior of a smaller planet? Answer: Small planets have a larger surface
area-to-volume ratio than larger planets.
◉ Which of the terrestrial worlds has the strongest magnetic field?
Answer: Earth
