The terrestrial planets are clearly distinguished from the
Jovian planets in terms of size and mass. Earth is the largest of the
terrestrial planets, with a diameter slightly larger than the diameter of Venus
and much larger than the diameter of either Mercury or Mars, while the Jovian
planets are all much larger than Earth, with diameters ranging from four to 11
times that of Earth. In addition, Earth has the most mass of all the
terrestrial planets, with slightly more mass than Venus and considerably more
mass than Mercury or Mars; the mass of each of the Jovian planets is
considerably more than that of Earth, ranging from masses around 15 times that
of Earth for Uranus and Neptune to slightly less than 100 times the mass of
Earth for Saturn and more than 300 times the mass of Earth for Jupiter. Another
difference is that the terrestrial planets are much denser than the Jovian ones
because the terrestrial planets are mainly rocks and metals, while the Jovian
planets are mainly gases with perhaps a small amount of rocky material.
Finally, the atmospheres of the terrestrial and Jovian planets present another
distinct contrast. Mercury essentially has no atmosphere, while Venus and Mars
have atmospheres that consist mostly of carbon dioxide, and Earth has a unique
atmosphere that is rich in oxygen and nitrogen. The Jovian planets have very
different atmospheres, mostly hydrogen and helium and various hydrogen
compounds.
Areas where the differences between the terrestrial and
Jovian planets are not so clear-cut are in terms of rotation and magnetic
field. All of the planets rotate, and in general they rotate in the same way:
their respective axes of rotation are basically perpendicular to their orbital
planes, and the planets rotate from west to east as they revolve around the
Sun. There are exceptions, however: Venus and Uranus rotate from east to west,
which is called retrograde rotation, and the rotation axis of Uranus lies almost
in the plane of its orbit, which basically means that it is rolling on its side
as it orbits the Sun. The Jovian planets rotate at higher speeds than do the
territorial planets, although the distinction between the two types of planets
is not so clear in this respect. The Jovian planets Jupiter and Saturn complete
rotations in approximately ten hours, which is considerably faster than the
59-day rotation period of Mercury
or the 243-day rotation period of Venus but not so much faster than the
approximately 24-hour rotation periods of Earth and Mars. There are also
not clear distinctions between Jovian and terrestrial planets in terms of
magnetic fields. Earth has a magnetic field, and so do many of the other
planets. The magnetic fields on Jupiter and Saturn are at least as strong as
the magnetic field on Earth (they could be stronger), yet Venus has no magnetic
field.
1. The word markedly in paragraph 1 is closest in
meaning to
2. The word challenging in paragraph 1 is closest in meaning to
3. Which of the following can be inferred from the passage? (write the letter in the box)
A. Earth's mass is less than that of Mars.
B. Saturn's mass is more than 100 times that of Mars
C. Mercury's mass is more than that of Venus.
D. Jupiter's mass is less than that of Saturn.
4. The word present in paragraph 2 could best be replaced by .
5. The phrase clear-cut in paragraph 3 is closest in meaning to .
6. Which of the sentences below expresses the essential information in the highlighted sentence in paragraph 3? (write the letter in the box)
A. Rotation periods on Venus are four times those on Mercury and ten times those on Earth.
B. All of the Jovian planets rotate more than ten times faster than all of the terrestrial planets.
C. The terrestrial planets have much shorter days than do Jupiter and Saturn.
D. Days on Earth and Mars are longer than days on Jupiter and Saturn but much shorter than days on Mercury and Venus
7. The phrase at least as strong as in paragraph 3 is closest in meaning to
8. Which factor does NOT distinguish the terrestrial planets from the Jovian planets?
9. Why does the author begin paragraph 4 with the question And what about Pluto? (write the letter in the box)
A. To indicate that Pluto has not been adequately covered in the previous material
B. To support the idea that Pluto is the smallest planet
C. To introduce the idea that Pluto is not really a planet
D. To indicate that not much is known about Pluto
10. The phrase these broad categories in paragraph 4 refers to
11. Select the appropriate phrases from the answer choices and match them to the type of planet to which they relate. TWO of the answer choices will NOT be used. This question is worth 3 points.
Terrestrial planets
Jovian planets
a. Are greater in size and in mass than Earth
b. Have a retrograde rotation
c. Are located between the Sun and the asteroid belt
d. Are less dense planets mainly composed of gases
e. Are less than or equal to the Earth in size and in mass
f. Have atmospheres similar to Earth's
g. Are located outside of the asteroid belt
h . Are denser planets mainly composed of solids
