Where did the elements heavier than hydrogen and helium come from? |
They were produced inside stars |
Why did the solar nebula heat up as it collapsed? |
As the cloud shrank, its gravitational potential energy was converted into kinetic energy and then into thermal energy |
Why did the solar nebula flatten into a disk? |
It flattened as a natural consequence of collisions between particles in the nebula, changing random motions into more orderly ones |
What happened during the accretion phase of the early solar system? |
Particles grew by colliding and sticking together |
According to our theory of solar system formation, why do all the planets orbit the sun in the same direction and in nearly the same plane? |
The laws of conservation of energy and conservation of angular momentum ensure that any rotating object, collapsing cloud will end up as a spinning disk |
What percentage of the solar nebulas mass consisted of hydrogen and helium gases? |
98 percent |
Why are the inner planets made of denser materials than the outer planets? |
In the inner part of the nebula only metals and rocks were able to condense because of the high temperatures, where as hydrogen compounds, although more abundant, were only able to condense in the cooler outer regions |
At first, the Sun’s only present-day rotation seems to contradict the prediction of the nebular theory because |
the theory predicts that the Sun should have been rotating fast when it formed, but the actual rotation is fairly slow |
According to our theory of solar system formation, why does the Sun rotate slowly today? |
The Sun once rotated much faster, but it transferred angular momentum to charged particles caught in its magnetic field and then blew the particles away with its strong solar wind |
According to the nebular theory, how did the Oort cloud form? |
It is made of planetismals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets |
According to the nebular theory, what are asteroids and comets? |
They are leftover planetismals that never accreted into planets |
What is the most likely reason that there are no giant planets beyond Neptune? |
By the time planetismals grew to large enough mass to hold onto an atmosphere, the solar nebula had been blown away |
Which of the following is the origen of almost all the large moons around the jovian planets? |
They were formed by condensation and accretion in a disk of gas around the planet |
The nebular theory of the formation of the solar system successfully predicts all but one of the following. Which one does the theory not predict? |
the equal number of terrestrial and jovian planets |
Suppose you find a rock that contains some potassium-40 (half life of 1.3 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? |
3.9 billion years |
The age of our solar system is approximately |
4.6 billions years |
Which of the following is not evidence supporting the giant impact theory for the formation of the Moon? |
Scientists have found several meteorites that appear to be the remains of the object that caused the giant impact |
According to our theory of solar system formation, why do we find some exceptions to the general rules and patterns of the planets? |
Most of the exceptions are the results of giant impacts |
According to the nebular theory, how did the Kuiper belt form? |
It is made of planetismals that formed beyond Neptune’s orbit and never accreted to form a planet |
What kind of material in the solar nebula could remain solid at temperatures as high as 1500 K, such as existed in the inner regions of the nebula? |
Metals |
Astronomy Ch 8
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