A) 0 percent
B) 0.1 percent
C) 2 percent
D) 20 percent
E) 80 percent
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A) 0 percent
B) 0.4 percent
C) 2 percent
D) 20 percent
E) 80 percent
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Ices would have condensed in the inner s...View Answer
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(a)All planets orbit the Sun countercloc...View Answer
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1.Larger planets should be in ...View Answer
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A) Planets orbit around the Sun in nearly circular orbits in a flattened disk.
B) the compositional differences between the terrestrial and jovian planets
C) the equal number of terrestrial and jovian planets
D) asteroids,Kuiper-belt comets,and the Oort cloud
E) the craters on the Moon
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A) the first few hundred million years after the planets formed,which is when most impact craters were formed
B) the time before planetesimals finished accreting into planets,during which many growing planetesimals must have shattered in collisions
C) the time during which heavy elements condensed into rock and metal in the solar nebula
D) the period about 65 million years ago when an impact is thought to have led to the extinction of the dinosaurs
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A) Nuclear fusion occurring in the core of the protosun produced energy that heated the nebula.
B) As the cloud shrank,its gravitational potential energy was converted to kinetic energy and then into thermal energy.
C) Radiation from other nearby stars that had formed earlier heated the nebula.
D) The shock wave from a nearby supernova heated the gas.
E) Collisions among planetesimals generated friction and heat.
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A) It was fairly flat to begin with,and retained this flat shape as it collapsed.
B) The force of gravity pulled the material downward into a flat disk.
C) the law of conservation of energy
D) It flattened as a natural consequence of collisions between particles in the nebula.
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A) was weaker than it is today.
B) was stronger than it is today.
C) was about the same strength as it is today.
D) was nonexistent.
E) blew outward only along the Sun's poles.
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A) 10,000 years
B) 4.6 million years
C) 4.5 billion years
D) 14 billion years
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A) Studies of the trajectories of nearby stars relative to the Sun show that the Sun is not in danger of a near-collision with any of them.
B) Stellar near-collisions are far too rare to explain all the planets now known to orbit nearby stars.
C) A near collision might have created planets,but it could not have created moons,asteroids,or comets.
D) A near collision should have left a trail of gas extending out behind the Sun,and we see no evidence of such a trail.
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A) There were no comets or asteroids in these first-generation star systems.
B) Jovian planets in these first-generation star systems had clouds made of water and other hydrogen compounds.
C) These first-generation star systems typically had several terrestrial planets in addition to jovian planets.
D) Like the jovian planets in our solar system,the jovian planets in these first-generation systems were orbited by rings.
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A) ice that condensed in the solar nebula in the region where Earth formed.
B) chemical reactions that occurred in Earth's crust after Earth formed.
C) chemical reactions that occurred in Earth's core after Earth formed.
D) material left behind during the giant impact that formed the Moon.
E) comets that impacted Earth.
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A) It got hotter,its rate of rotation increased,and it flattened into a disk.
B) Its mass,temperature,and density all increased.
C) It gained energy,it gained angular momentum,and it flattened into a disk.
D) Its gas clumped up to form the terrestrial planets,nuclear fusion produced heavy elements to make the jovian planets,and central temperatures rose to more than a trillion Kelvin.
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A) the moons of Mars
B) asteroids
C) Kuiper belt comets
D) Oort cloud comets
E) all of the above
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