EAPS 105 STUDY GUIDE ANSWERS AND QUESTIONS
SET A+
✔✔The origin of Saturn's E-ring - ✔✔water ice ejected from Enceladus' cryovolcanic
eruptions at escape velocities
✔✔What controls the minimum impact velocity of an asteroid - ✔✔the minimum impact
velocity of an asteroid is the escape velocity of the planet or moon being impacted
✔✔Why impacts into Mercury are the fastest - ✔✔close proximity to the Sun which
gives a big gravitational assist
✔✔The typical range of speeds of asteroid and comet impacts - ✔✔1 kilometer/second-
70 kilometers/second
✔✔The general relationship between impactor and crater size - ✔✔impact craters are
10-30 times larger than the impactors
✔✔Why most craters are round - ✔✔because impacts act as explosions
✔✔The three stages of impact catering - ✔✔contact and compression, excavation, and
modification
✔✔What a transient crater is - ✔✔the maximum crater size that occurs at the end of the
excavation stage
✔✔The general characteristics of simple and complex impact craters - ✔✔simple
craters: circular bowl-shaped depressions
complex crater: central peak is a flat floor covered by breccia and melt, rim is terraced
(stepped) because rim rocks are not strong enough to support the steep walls of the
transient crater
✔✔The general extent of an eject blanket - ✔✔surrounding plain is blanketed with
ejecta for a distance of about one crater diameter
, ✔✔What crater rays are - ✔✔lines of impact ejecta that extend very far from the impact
site
✔✔Why young craters appear brighter than older ones - ✔✔due to the excavation of
brighter material beneath the surface, once exposed to space, this material darkens due
to space weathering
✔✔Why Earth has so few recognizable impact craters compared to the Moon - ✔✔The
Moon has no erosional processes to erase old impact craters
✔✔Why the Kentland Crater does not look like a crater - ✔✔impact was before the last
glaciation period so glaciers flattened it when they covered Indiana, very beneficial and
gave easy access to limestone and deep rocks
✔✔The evidence that an asteroid impact wiped out the dinosaurs - ✔✔the thin layer of
clay that seperates Cretaceous from Paleogene sediments all over the world contains a
lot of iridium, shocked quartz, and soot, indicative of a giant impact and global fire
✔✔How often very large (10 km diameter) asteroids hit the Earth - ✔✔every hundred
million years
✔✔About how many Near Earth Asteroids are we currently tracking - ✔✔20,000 we are
currently tracking
✔✔Strategies for changing the orbit of asteroids and comets on a collision course with
Earth - ✔✔1. kinetic impact: crash a heavy spacecraft into it to alter trajectory
2. spacecraft propulsion: create a small sustained thrust to alter trajectory
3. solar sail: attach a large solar sail enabling solar pressure to shift the object's
trajectory
4. nuclear weapons: direct hit to vaporize or detonate a series of devices alongside to
alter trajectory
5. focus solar heat onto a comet surface to create a thrust from the resulting
vaporization of material and alter trajectory
✔✔ The consequences of a planet or moon being hot inside - ✔✔differentiation,
volcanism, plate tectonics, magnetic fields
✔✔How hot the Earth is on the inside compared to the surface of the Sun - ✔✔the inner
core is almost as hot as the surface of the Sun, but is solid because the higher pressure
raises the melting temperature
✔✔The relationship between heat and motion in atoms - ✔✔when an object is stopped,
the kinetic energy is converted into atomic scale motion (vibration of atoms), which is
the very definition of heat
SET A+
✔✔The origin of Saturn's E-ring - ✔✔water ice ejected from Enceladus' cryovolcanic
eruptions at escape velocities
✔✔What controls the minimum impact velocity of an asteroid - ✔✔the minimum impact
velocity of an asteroid is the escape velocity of the planet or moon being impacted
✔✔Why impacts into Mercury are the fastest - ✔✔close proximity to the Sun which
gives a big gravitational assist
✔✔The typical range of speeds of asteroid and comet impacts - ✔✔1 kilometer/second-
70 kilometers/second
✔✔The general relationship between impactor and crater size - ✔✔impact craters are
10-30 times larger than the impactors
✔✔Why most craters are round - ✔✔because impacts act as explosions
✔✔The three stages of impact catering - ✔✔contact and compression, excavation, and
modification
✔✔What a transient crater is - ✔✔the maximum crater size that occurs at the end of the
excavation stage
✔✔The general characteristics of simple and complex impact craters - ✔✔simple
craters: circular bowl-shaped depressions
complex crater: central peak is a flat floor covered by breccia and melt, rim is terraced
(stepped) because rim rocks are not strong enough to support the steep walls of the
transient crater
✔✔The general extent of an eject blanket - ✔✔surrounding plain is blanketed with
ejecta for a distance of about one crater diameter
, ✔✔What crater rays are - ✔✔lines of impact ejecta that extend very far from the impact
site
✔✔Why young craters appear brighter than older ones - ✔✔due to the excavation of
brighter material beneath the surface, once exposed to space, this material darkens due
to space weathering
✔✔Why Earth has so few recognizable impact craters compared to the Moon - ✔✔The
Moon has no erosional processes to erase old impact craters
✔✔Why the Kentland Crater does not look like a crater - ✔✔impact was before the last
glaciation period so glaciers flattened it when they covered Indiana, very beneficial and
gave easy access to limestone and deep rocks
✔✔The evidence that an asteroid impact wiped out the dinosaurs - ✔✔the thin layer of
clay that seperates Cretaceous from Paleogene sediments all over the world contains a
lot of iridium, shocked quartz, and soot, indicative of a giant impact and global fire
✔✔How often very large (10 km diameter) asteroids hit the Earth - ✔✔every hundred
million years
✔✔About how many Near Earth Asteroids are we currently tracking - ✔✔20,000 we are
currently tracking
✔✔Strategies for changing the orbit of asteroids and comets on a collision course with
Earth - ✔✔1. kinetic impact: crash a heavy spacecraft into it to alter trajectory
2. spacecraft propulsion: create a small sustained thrust to alter trajectory
3. solar sail: attach a large solar sail enabling solar pressure to shift the object's
trajectory
4. nuclear weapons: direct hit to vaporize or detonate a series of devices alongside to
alter trajectory
5. focus solar heat onto a comet surface to create a thrust from the resulting
vaporization of material and alter trajectory
✔✔ The consequences of a planet or moon being hot inside - ✔✔differentiation,
volcanism, plate tectonics, magnetic fields
✔✔How hot the Earth is on the inside compared to the surface of the Sun - ✔✔the inner
core is almost as hot as the surface of the Sun, but is solid because the higher pressure
raises the melting temperature
✔✔The relationship between heat and motion in atoms - ✔✔when an object is stopped,
the kinetic energy is converted into atomic scale motion (vibration of atoms), which is
the very definition of heat
