48 terms

CH. 7 Our Planetary System

stars and galaxies test #2
STUDY
PLAY
Rank the objects from left to right based on their average distance from the Sun, from farthest to closest.
pluto (farthest), neptune, uranus, saturn, jupiter, mars, earth, venus, mercury (closest)
Rank these objects from left to right based on their mass, from highest to lowest. (Not to scale.)
Sun (highest mass), Jupiter, Earth, Mars, Mercury, Pluto (lowest mass)
Rank these objects by size (average equatorial radius), from largest to smallest. (Not to scale.)
Sun (largest radius), Jupiter, Earth, Mars, Mercury, Pluto (smallest radius).
Rank these planets from left to right based on their average surface (or cloud-top) temperature, from highest to lowest. (Not to scale.)
mercury (highest temperature), earth, mars, jupiter, neptune (lowest temperature).

Notice that, for these five planets, temperature correlates with distance from the Sun: the closer to the Sun, the hotter the planet. Remember, however, that this is not always the case, because a planet's temperature also depends on its reflectivity and on the strength of its greenhouse effect (if any). For example, the greenhouse effect gives Venus a higher average temperature than Mercury, even though Venus is nearly twice as far from the Sun.
Rank these planets from left to right based on the amount of time it takes them to orbit the Sun, from longest to shortest. (Not to scale.)
Recall that the time it takes a planet to orbit the Sun is called its orbital period, and that Kepler's third law tells us that orbital period increases with distance from the Sun. That is why the ranking order for orbital period is the same as the ranking order for distance from the Sun.

neptune (longest time), jupiter, mars, earth, mercury (shortest time)
Rank these planets from left to right based on the number of moons that orbit them, from highest to lowest. (Not to scale.)
jupiter (highest #), mars, earth, mercury (lowest #)

Jupiter has many moons as a consequence of its formation, in which moons formed in a disk of material surrounding it and its extended atmosphere at the time allowed it to capture numerous small bodies into orbit. Mars has two very small moons that it presumably captured at a time when it, too, had an extended atmosphere. Earth's single but surprisingly large moon is thought to have formed as a result of a giant impact. Mercury (and Venus) have no moons.
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.

(we expect terrestrial planets to form close to a star and jovian planets to form farther out).
Compared to terrestrial planets, jovian planets are __________.
more massive and lower in average density.
Which planet is approximately halfway between Pluto's orbit and the Sun?
Uranus, the 7th planet from the Sun.

(Notice that Uranus is located at an average distance of 19.2 AU, which is close to half of Pluto's average distance of 39.5 AU. Many people are surprised to realize that Uranus, the seventh planet from the Sun, is only half as far as Pluto. As you can see in the figure, this surprising fact arises because the outer planets are much more widely spaced than the inner planets).
The dwarf planet Eris was discovered in 2005, orbiting the Sun at an average distance about twice that of Pluto. In which of the following ways do Pluto and Eris differ from the terrestrial and jovian planets in our solar system?
-Both Pluto and Eris are smaller than any of the terrestrial planets.

-Both Pluto and Eris travel in more elliptical orbits than any of the terrestrial or jovian planets.

-Both Pluto and Eris are less massive than any of the terrestrial or jovian planets.
which of the following is not one of the four major features of the solar system?
The solar system contains eight planets plus dwarf planets (including Ceres, Pluto, and Eris).
Which of the following correctly describe patterns of motion in the solar system?
-Planets closer to the Sun move around their orbits at higher speed than planets farther from the Sun.

-All the planets (not counting Pluto) orbit the Sun in nearly the same plane.

-All the planets (not counting Pluto) have nearly circular orbits.
Now consider the second major characteristic (two types of planets). Which of the following statements are true?
-Jovian planets are larger in size than terrestrial planets.

-Jovian planets orbit farther from the Sun than terrestrial planets.

-Jovian planets are larger in mass than terrestrial planets.

-Jovian planets have more moons than terrestrial planets.
The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region(s) of the solar system that we call __________.
-the asteroid belt
-the Kuiper belt
-the Oort Cloud

(Most asteroids are found in the asteroid belt between Mars and Jupiter. Comets are found in two regions: the Kuiper belt just beyond the orbit of Neptune and the much more distant and spherically shaped region known as the Oort cloud).
All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major characteristics of the solar system?
-Venus rotates in a direction opposite to the rotation of the other terrestrial planets.

-Uranus rotates with an axis tilt that lies nearly in the ecliptic plane.

-Our Moon has a diameter more than 1/4 the diameter of Earth.
Scientifically, which of the following possible conclusions is justified from the patterns of motion alone?
he planets were not each born in a separate, random event.
Now consider why the observed patterns of motion lead to the conclusion that the planets were not born in separate, random events. The reason for this conclusion is that, if the planets had been born in separate, random events, we would expect that __________.
planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane.
Today, scientists have a theory (the nebular theory) that explains all the major characteristics of the solar system. In science, we expect a theory like this not only to explain the observed characteristics of our solar system but also to __________.
make testable predictions about other solar systems.
Listed following are characteristics that can identify a planet as either terrestrial or jovian. Match these to the appropriate category.
Terrestrial planets= small size
=located within the inner solar system
=solid, rocky surface

Jovian planets= primarily composed of hydrogen, helium, and hydrogen compounds
=extensive ring systems
=numerous orbiting moons
=low average density
_______ is about 30 times as far from the Sun as our own planet.
Neptune
________ is the planet with the highest average surface temperature.
Venus
The planet with the lowest average density is ________.
Saturn
The planet that orbits closest to the Sun is _________.
Mercury
The only rocky planet to have more than one moon is _______.
Mars
________ is the jovian planet that orbits closest to the Sun.
Jupiter
________ has a rotational axis that is tilted so much it lies nearly in the plane of its orbit.
Uranus
Most of the surface of ________ is covered with liquid water.
Earth
T/F: We could probably learn more about Mars by sending a new spacecraft on a flyby than by any other method of studying the planet.
False
How do you know this is Saturn?
b/c of its colors and bright, wide rings.

(Although all four jovian planets have rings, Saturn's rings are by far the widest and brightest, and hence the only ones easily visible in photographs).
Which of the following is not a major pattern of motion in the solar system?
Nearly all comets orbit the Sun in same direction and roughly the same plane.----This statement is untrue because comets of the Oort cloud, which are the most numerous of all comets, have randomly oriented orbits going in all directions around the Sun.
Which of the following IS a major pattern of motion in the solar system?
-Most of the solar system's large moons orbit in their planet's equatorial plane.

-The Sun and most of the planets rotate in the same direction in which the planets orbit the Sun.

-All of the planets orbit the Sun in the same direction - counterclockwise as viewed from above Earth's north pole.
Which of the following is not a major difference between the terrestrial and jovian planets in our solar system?
Terrestrial planets contain large quantities of ice and jovian planets do not.---Terrestrial planets actually contain very little ice, because they are made mostly of metal and rock.
Consider the following statement: "Rocky asteroids are found primarily in the asteroid belt and Kuiper belt while icy comets are found primarily in the Oort cloud." What's wrong with this statement?
The Kuiper belt contains icy comets, not rocky asteroids.
Which of the following is not a real difference between asteroids and comets?
Asteroids orbit the Sun while comets just float randomly around in the Oort cloud.--- just "floating randomly" is not possible for an object under the influence of the Sun's gravity - any such object must follow one of the orbits allowed by the law of gravity
Which of the following IS a real difference between asteroids and comets?
-It is thought that comets are far more numerous than asteroids.

-Asteroids are made mostly of rock and comets are made mostly of ice.

-Most asteroids are located much nearer to the Sun than most comets.
The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?
The diameter of Earth's Moon is about 1/4 that of Earth.
Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is ______.
much larger
Einstein's famous equation, E=mc 2, explains the fact that __________.
the Sun generates energy to shine by losing some 4 million tons of mass each second
Venus has a higher average surface temperature than Mercury. Why?
Because its surface is heated by an extreme greenhouse effect.
In what way is Venus most similar to Earth?
Both planets are nearly the same size.
Which of the following statements about the recently-discovered object Eris is not true?
It is thought to be the first example of a new class of object.
Which of the following statements about the recently-discovered object Eris IS true?
-It orbits the Sun in the same direction as the other planets.

-It is slightly larger than Pluto.

-It lies well beyond Pluto and Neptune.
Mars has two moons that are most similar in character to:
small asteroids
Imagine that an alien spaceship crashed onto Earth. Which statement would most likely be true?
It would crash in the ocean.
Which planet listed below has the most extreme seasons?
Uranus
In what way is Pluto more like a comet than a planet?
it is made mostly of rock and ice
Why was it advantageous for the Voyager mission to consist of flybys rather than orbiters?
Each individual spacecraft was able to visit more than one planet.
Why has NASA sent recent orbiters to Mars (such as Mars Reconnaissance Orbiter) on trajectories that required them to skim through Mars's atmosphere before settling into their final orbits?
It saves money because the spacecraft uses atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines.