AST CH 4

The planets in our solar system are thought to have come fromthe same cloud of gas and dust in which the Sun formed
What is the main reason that Earth’s composition is different from Jupiter’s?Compared to Jupiter, Earth formed in a hotter region, where only rocks and metals could exist as solids
As the solar nebula collapsed, it became a disk becausethe overall rotation of the nebula plus collisions between particles made the particles go in more or less the same direction
The jovian planets contain large abundance of hydrogen and helium becausebeyond the front line, the gravity of large, ice-rich planetesimals captured the abundant H and He gas
Because of the temperatures in the protoplanetary disk,rocks and metals froze in both the inner and outer regions, and ice froze only in the outer region
As the solar system nebula collapsed under its own gravityit heated and spun up
Suppose the solar nebula had cooled much more before the solar wind cleared away the remaining gas. In that case, the terrestrial planets likely would have ended up:with a higher abundance of hydrogen compounds and larger size
If the solar nebula initially had no angular momentumthere would not be any planets orbiting the Sun
Suppose the solar nebula had been too warm for ices to condense anywhere. If a planet had still formed at Jupiter’s location, it most likely would havebeen similar in composition to Earth, with a much smaller mass than the real Jupiter
Terrestrial Planetssmall size; solid, rocky surface; located within the inner solar system
Jovian Planetsprimarily composed of hydrogen, helium, and hydrogen compounds; extensive ring systems; numerous orbiting moons; low average density
Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets?Terrestrial planets will likely be located nearer the planetary system’s star than any Jovian planets
Compared to terrestrial planets, jovian planets aremore massive and lower in average density
Which planet is approximately halfway between Pluto’s orbit and the Sun?Uranus, the seventh planet from the Sun
In which of the following ways do Pluto and Eris differ from the terrestrial and jovian planets in our solar system?-Smaller than any of the terrestrial planets
-Travel in more elliptical orbits than ay of the terrestrial or jovian planets
-Less massive than any of the terrestrial or jovian planets
What substances were found within the inner 0.3 AU of the solar system before planets began to form?Rocks, metals, hydrogen compounds, hydrogen, and helium, all in gaseous form
What substances existed as solid flakes within the inner 0.3 AU of the solar system before planets began to form?none
Where would you expect terrestrial planets to form in the solar nebula?Anywhere between 0.3 AU and the frost line
The jovian planets are thought to have formed as gravity drew hydrogen and helium gas around planetesimals made ofrocks, metals, and ices
Terrestrial planets-Accreted from planetesimals of rock and metal
-Surfaces dramatically altered during the heavy bombardment
Jovin planets-Accreted from icy planetesimals
-Formed in a region of the solar system with lower orbital speeds
-Large moons formed in surrounding disks of material
-Ejected icy planetesimals that are now Oort cloud comets
Our solar system was created by the gravitational collapse of thesolar nebula
Our moon was most likely formed by a collision between Earth and a Mars sizedplanetesimal
The first few hundred million years of the solar system’s history were the time of __________________ during which Earth suffered many large impacts.heavy bombardment
Mars was formed by the __________________ of smaller objects.accretion
The era of planet formation ended when the remaining hydrogen and helium gas of the solar nebula was swept into interstellar space by thesolar wind
Ice can form from a gas through the process ofcondensation
Hydrogen compounds in the solar system can condense into ices only beyond thefrost line
__________________________ allows us to determine the age of a rockradiometric dating
Which of the following three kinds of objects resides closer to the Sun on average?Asteroids
Planetary orbits in our solar system arefairly circular and in the same plane
Which have more moons on average?Jovian planets
All four of the giant outer planets: Jupiter, Saturn, Uranus, and Neptune- have rings. T/FTrue
All planets orbit the Sun in the same direction (counterclockwise as viewed from above Earth’s North Pole) T/FTrue
All the planets in the solar system have at least one moon. T/FFalse
The more massive planets in the solar system tend to be less dense than the lower mass planets. T/FTrue
All comets orbit the Sun in the same direction as the planets. T/FFalse
Suppose that the Sun shrank in size, but its mass remained the same. What would happen to Earth’s orbit?Earth’s orbit would be unaffected
Which planet listed below has the most extreme seasons?Uranus
List the planets of our solar system in the correct order from closest to farthest from the Sun.Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
Which is NOT a characteristic of the outer planets?They have very few, if any, satellites.
The terrestrial planets are made almost entirely of elements heavier than hydrogen and helium. According to modern science, where did these elements come from?They were produced by stars that lived and died before our solar system was born.
Solar nebula:98% hydrogen and helium
Which lists the major steps of solar system formation in the correct order?Collapse, condensation, accretion
Which of the following did not occur during the collapse of the solar nebula?Concentrating denser materials nearer the Sun
What’s the leading theory for the origin of the Moon?It formed from the material ejected from Earth in a giant impact
Which of the following types of material can condense into what we call ice at low temperatures?Hydrogen compounds
What do we mean by the frost line when we discuss the formation of planets in the solar nebula?It is a circle at a particular distance from the Sun, beyond which the temperature was low enough for ices to condense
According to our present theory of solar system formation, which of the following explains why the solar system nebula ended up with a disk shape as it collapsed?It flattened as a natural consequence of collisions between particles in the nebula.
According to our theory of solar system formation, what are asteroids and comets?Leftover planetesimals that never accreted into planets.
According to modern scientific dating techniques, approximately how old is the solar system?4.5 billion years
What is the giant impact hypothesis for the origin of the Moon?The moon formed from material blasted out of Earth’s mantle and crust by the impact of a Mars-sized object.
Suppose you start with 1 kilogram of a radioactive substance that has a half-life of 10 years. Which of the following statements will be true after 20 years pass?You’ll have 0.25 kilogram of the radioactive substance remaining.
The planet in our solar system with the highest average surface temperature is _________________Venus