astronomy 121|230 Quiz Questions
Correctly Answered
-- Life, orbital resonances, rings and gaps. - ✔ ✔ Give three examples of current properties of the
solar system that a model of its formation need not explain. Why?
11. How did the temperature structure of the solar nebula affect the planetary composition? - ✔ ✔ -
- The distance between a planet and the sun determines the temperatures at which each planet was
created. For planets close to the Sun like Mercury and Venus, the temperature was too high for those
planets to be formed with light compounds which prevented them to accrete and hold hydrogen. For
the Jovian planets, they were made at temperatures that were too low to support rocky compositions.
Their ability to hold hydrogen gas allowed them to accrete and become much larger.
Are all asteroids found in the asteroid belt? Explain. - ✔ ✔ No. Earth-crossing asteroids (influenced
by nearby Mars and Jupiter) intersect with Earth's orbit.
By comparison with its average density, what do the densities of water and the Earth's crust tell us
about the interior? - ✔ ✔ -- Because the density of water is much less than the average density of
Earth, we can conclude that the much denser material must lie deeper, under the Earth's surface and
that much of the Earth's interior is made up of very dense matter.
Comets vaporize in the Earth's atmosphere. How do we know their composition? - ✔ ✔ -- When they
vaporize in the Earth's atmosphere they emit light and radiation which can be analyzed to determine
what they are composed of.
Compare and contrast P-waves and S-waves, and explain how they are useful in geology. - ✔ ✔ -- P
Waves: Pressure waves that alternately expand and compress the material medium through which they
move.
-- S Waves: Shear waves which vibrate the material which they pass back and forth and cause a side-to-
side motion. S-Waves cannot travel through liquid.
-- They are useful in geology because they geologists can measure the time taken for the waves to move
from the site of an earthquake to one or more monitoring stations on Earth's surface which can help
determine the density of matter in the interior.
Compare and contrast the atmospheres and weather systems of Saturn and Jupiter, and tell how the
differences affect each planet's appearance. - ✔ ✔ -- Both have large and violent storms present,
though Jupiter's Great Red Spot is more constant. Saturn's storms are more short-lived.
-- Because Saturn's atmosphere is so thick, its colors are not as distinct.
,Compare and contrast the evolution of the atmospheres of Mars, Venus, and Earth. - ✔ ✔ -- All three
have secondary atmospheres created by volcanoes.
-- Venus, which is closest to the Sun, experienced temperatures which prevented the CO2 from settling
out of the atmosphere and dissolve into the oceans. Venus became a victim of the runaway greenhouse
effect and the H2O in the atmosphere was destroyed by UV sunlight.
-- Earth was far enough from the Sun that liquid water could form, eventually creating oceans, which
dissolved much of the CO2 present in the atmosphere. The small amounts of H2O and CO2 in the Earth's
atmosphere create an insulating layer that creates a greenhouse effect which is just enough to keep the
Earth warm and liquid.
-- Mars once had liquid water and enough water to dissolve the CO2 in the atmosphere, but because it
was less massive than Venus or Mars it lost its CO2. Once Mars lost its CO2, the atmosphere thinned to
the point that most of the IR radiation escaped. Also, Mars's volcanism stopped very early in its
formation which prevented the atmosphere from having its H2O and CO2 renewed.
Compare and contrast Titan with Jupiter's Galilean moons. - ✔ ✔ -- Scientists believe that Titan is
most similar to Ganymede and Callisto, because the three moons have quite similar masses and radii,
and thus average densities.
-- Titan's core is probably made of rock which is surrounded by a thick mantle of water ice. In this way,
Titan is much more similar to Ganymede than Callisto, which is made up almost uniformly of rock and
ice. This composition is much different than the ones found on Io and Europa, which are made of rocky
mantles and metallic cores.
Compare the properties of Pluto with those of the Terrestrial and Jovian planets. How would you classify
Pluto and why? - ✔ ✔ -- Pluto is much smaller than T and J planets.
-- Pluto much more compatible with an icy Jovian moon.
-- Pluto is made of carbonaceous material.
Compare the sizes of the Earth, Sun, Milky Way Galaxy, and the Universe as a whole. - ✔ ✔ -- Earth =
15,000 km
-- Sun = 1,500,000 km
-- Milky Way = 100,000 light years
-- Universe = 100,000,000 light years
Define 'Escape Speed'. - ✔ ✔ The speed necessary for an object to escape the gravitational pull of an
object. Anything that moves away from the object with more than the escape speed will never return.
, Describe a day on Titania. - ✔ ✔ -- Titania is a heavily cratered moon with little indication of
geological activity. Titania's low reflectivity suggests that the moon's surface is quite dirty. You would be
very cold.
Describe a possible history of a comet, observable from Earth, starting with its birth in the solar nebula
near Jupiter. - ✔ ✔ -- Comet is subjected to repeated "gravity assists" from Jovian planets and is
eventually flung into orbits taking them far from the Sun into the Kuiper Belt, where it is later sent on a
trajectory back toward the center of the system.
Describe a widely accepted theory of the Moon's origin. - ✔ ✔ -- Impact theory: The proto-Earth
collided with a Mars-sized object, and debris was captured by gravity and set into orbit.
Describe one observational problem associated with Venus's near resonance of rotation and orbit. - ✔
✔ -- Venus rotates almost exactly five time between one closest approach to Earth and the next which
means that it presents nearly the same face to Earth at the closest approach. This means that we have
much more information on one side of the planet than on the other side.
Describe some ways that random processes affected the properties of planets. - ✔ ✔ Mercury's
large nickel-iron core may be the result of a collision between two partially differentiated protoplanets.
While the cores may have merged, much of the mantle may have been lost.
Two large bodies could have merged to form Venus, giving it its abnormally low rotation rate.
The Earth-Moon system may have been formed by a collision between the proto-Earth and a Mars-sized
object.
Describe the atmospheric conditions in the Southern Hemisphere of Mars during the summer. - ✔ ✔
-- Martian summers in the Southern Hemisphere are significantly colder than those that you would
find in the Northern Hemisphere. The temperature would be somewhere lower than 150K and giant
dust storms would rage in the SH blowing northward.
Describe the basic features of the condensation theory of the formation of the solar system. - ✔ ✔ --
Condensation theory combines features of the nebular theory (a large cloud of interstellar gas began to
collapse under the influence of its own gravity. As it contracted, it became denser and hotter, eventually
forming the Sun at the center with the cooler material becoming matter that made up the rest of what is
now in the solar system) with new information about interstellar dust grains, which acted as
condensation nuclei. After the solar nebula formed, cooled dust grains formed condensation nuclei
around which matter began to accumulate. As they grew larger collisions and accumulation increased
until fragmentation occurred and planets formed.
Describe the Earth's magnetosphere, and describe how it was discovered. - ✔ ✔ -- The Earth's
magnetosphere is a region in space whose shape is determined by the Earth's internal magnetic field,
the solar wind plasma, and the interplanetary magnetic field. The Earth's magnetosphere protects the
ozone layer from the solar wind. Explorer 1 first measured the Earth's magnetosphere in the 1950's.
