Deck 17: Impacts With Space Objects

Question 1

Evidence for the impact that occurred near Chicxulub,Mexico,includes all but which of the following?

A)quartz grains with shocked crystal structures,indicating a short and violent impact
B)iridium anomaly at roughly 100 sites worldwide in a thin layer of rock 65 million years old
C)sand-sized spherules of minerals suggesting a melting and resolidification of rock
D)large pieces of meteorite found in Mexico
E)The K/T boundary clays have a different composition from clays in the limestone layers above and below it;they might be explained by a mixture of one part asteroid to ten parts Earth crust

Answer 1

D

Question 2

Likely effects of the Cretaceous-Tertiary boundary impact include all but which of the following?

A)a stratospheric dust cloud that lasted 3-6 months
B)massive fires from the heat of the blast and from molten material
C)oxides of nitrogen formed by the compressive shock wave,forming HNO₃ in the atmosphere
D)significant long-term cooling in the oceans but warming in continental areas
E)total extinction of all land animals with a body mass of more than about 10 kg

Answer 2

D

Question 3

Relatively few impact craters have been discovered on Earth because _______________.

A)most rocks are too resistant to crater
B)the gravitational field is too weak
C)weathering,erosion,and tectonic processes mask them
D)bolides are very rare in this region
E)Jupiter is so large it deflects them away from Earth

Answer 3

C

Question 4

Comets are composed of ___________________.

A)ice and rocky debris
B)gas,mostly hydrogen and helium
C)solid rock,mostly andesite
D)electro-magnetic plasma
E)mostly organic material

Question 5

The space between Mars and Jupiter is occupied by ______.

A)bolides
B)meteorites
C)asteroids
D)comets
E)ejecta

Question 6

The planets and the asteroid belt orbit the Sun ____________________.

A)in a spherical distribution,whereas the Oort cloud of comets orbits in a plane
B)in a spherical distribution similar to that of the Oort cloud of comets
C)in planes tilted at an angle to the plane of the Oort cloud of comets
D)in planes,whereas the Oort cloud of comets has a spherical distribution
E)in orbits nearly identical to the Oort cloud of comets

Question 7

In 1994,the comet Shoemaker-Levy crashed with spectacular results into _____________.

A)Saturn
B)Mars
C)Titan
D)Jupiter
E)Venus

Question 8

The numbers of incoming objects are related to their size:

A)the smaller the meteoroids,the greater their abundance
B)the larger the meteoroids,the greater their abundance
C)the number is the same for each size range
D)the size is inversely proportional to the number

Question 9

A major comet or meteorite impact occurred in Mexico at the time boundary between the _______________.

A)Pleistocene and Pliocene
B)Precambrian and Cambrian
C)Cretaceous and Tertiary
D)Pliocene and Miocene
E)Jurassic and Cretaceous

Question 10

Venus resembles Earth in size,density,and distance from the Sun,but has a dense cloud cover of CO_2. Its air temperature is _________ that on Earth.

A)warmer than
B)cooler than
C)about the same as
D)there is no air on venus

Question 11

A comet's tail __________________.

A)lines up with the solar wind moving outward from the Sun
B)points toward the nearest planet as a result of its gravity
C)is a vapor trail behind a comet that points in the direction from which the comet came
D)always points toward the Sun
E)is composed of smoke from the burning comet

Question 12

Critical evidence for the Cretaceous-Tertiary boundary impact included _________________.

A)dinosaur fossils worldwide just above the layer of impact debris
B)an iridium anomaly in a thin layer of rock 65 million years old
C)recovery of very large pieces of meteorite
D)discovery of a crater covered by jungle vegetation in Brazil
E)an Iranian deposit of reddish iron bearing strata

Question 13

Asteroids lie mostly __________________.

A)between Mars and Jupiter
B)between the inner and outer planets
C)beyond Pluto,and in the Van Halen Belt
D)between Mercury and the Sun
E)Both between Mars and Jupiter and between the inner and outer planets are correct

Question 14

Stony meteorites are less commonly collected than iron meteorites because _______________.

A)they break up more readily while passing through the Earth's atmospheric filter
B)those that reach the ground are weathered and destroyed more rapidly
C)they are not as easily recognized
D)All of these choices are correct
E)None of these choices are correct

Question 15

Halley's comet has an average orbital period of ________________.

A)76 years
B)1 year
C)577 years
D)about 10,000 years
E)about 100,000 years,coinciding with average ice-age periods

Question 16

When a meteorite large enough to cause a crater hits the Earth,the size of the impact crater is ________________.

A)smaller than the meteorite
B)perhaps 10-20 times the diameter of the meteorite
C)about the same as the meteorite
D)determined by the angle of impact
E)determined mostly by the rock type at the point of impact

Question 17

Venus resembles Earth in size,density,and distance from the Sun,but has a dense cloud cover of ______.

A)CO2
B)hydrochloric-acid
C)methane
D)ozone
E)hydrogen-sulfide

Question 18

The solar wind is ___________________.

A)what causes visible dust storms on Mars
B)wind blowing on the surface of the Sun
C)wind blowing within the Sun's dense gas below the surface
D)the stream of subatomic particles flying outward from the Sun
E)a blast of sunspot energy

Question 19

When space debris blazes through the Earth's atmosphere as a streak of light or shooting star,it is referred to as a _______________.

A)moonlet
B)falling star
C)sunspot
D)meteor
E)starlet

Question 20

Why are there so many more impact craters visible on the Moon than on the Earth?

A)The moon has been hit by many more meteorites than the Earth,particularly the >1 km diameter bodies that create the biggest craters
B)The moon formed long before the earth formed,so has had more time to be hit by meteorites
C)The moon is made out of softer rock than the Earth that is more readily deformed when impacted by meteorites
D)Because of gravitational effects,the moon deflects many of the meteorites that would otherwise hit the Earth
E)Craters on the Earth can be destroyed by erosion and mountain-building processes,or obscured by vegetation or sedimentation

Question 21

The four inner planets are small,close together,near the Sun,and rocky.

Question 22

The 1-cm-thick clay layer that marks the Cretaceous/Tertiary (K/T)boundary has a high percentage of the element ________ in the clay layer,an enrichment about 300 times greater than the normal abundance.

A)iridium
B)silicon
C)iron
D)oxygen
E)zircon

Question 23

Most of the meteorites collected on the Earth's surface are "irons".

Question 24

The nearer an icy comet approaches the Sun,the smaller its tail becomes.

Question 25

Asteroids are distinguished from meteorites by their composition.

Question 26

Space debris that collides with the Earth comes primarily from fragmented asteroids and secondarily from comets.

Question 27

The outer planets lie at great distances from the Sun,and are composed mainly of hydrogen and helium gas surrounding rocky cores (except for Pluto);they commonly are orbited by icy moons and rings of icy debris with compositions of water (H₂O),ammonia (NH₃),carbon dioxide (CO₂),and methane (CH₄).

Question 28

Clusters of asteroids such as the Apollos have orbits that intersect Earth's orbit;there are more than a thousand mountain-sized Apollo asteroids that could hit the Earth.

Question 29

Evidence demonstrating that the crater in Arizona formed by meteorite impact includes all but which of the following?

A)The crater is steep-sided and closed
B)The rim of surrounding rock was created by uplifting the horizontal sedimentary-rock layers of the region and tilting them away from the crater
C)Little hills of rock outside the crater rim are inverted piles of the rock sequence exposed in the crater walls
D)Huge blocks of limestone are strewn around outside the crater
E)A 550-ton spherical piece of nickel-iron metallic meteorite was found in the bottom of the crater

Question 30

The most famous of the comets is the one carrying Edmund Halley's name,the man who calculated its orbit in 1682 and predicted its return to the inner solar system.

Question 31

The major types of meteorites are either "irons" (metallic)or "stones" (rocky).

Question 32

A comet may travel 100,000 astronomical units away during its orbit (an astronomical unit is 93 million miles,the distance between Earth and Sun).

Question 33

The Moon has plate tectonics,but no water or agents of erosion,and no life.

Question 34

Some students in this class will likely live long enough to see a return of Halley's comet.

Question 35

As a comet curves around the Sun,its tail rotates also,always pointing away from the direction in which the comet is heading.

Question 36

The world's classic meteorite crater lies on an arid portion of the Colorado Plateau in __________________.

A)Wyoming
B)Colorado
C)Utah
D)New Mexico
E)Arizona

Question 37

The solar system is surrounded by the Oort cloud composed of about a trillion comets,icy objects with orbits that take them far beyond the outermost planets of our solar system.

Question 38

The solar system has 11 known planets in orbit around the Sun.

Question 39

Halley's comet contains carbon (C),hydrogen (H),oxygen (O),and nitrogen (N)in ratios similar to that in the human body.

Question 40

A comet's tail is produced by the charged particles of the solar wind acting on comet ices.

Question 41

Some asteroids are not solid bodies,but rather "rubble piles" held together by the mutual gravitational attraction of all the individual pieces.

Question 42

Abundant large diamonds,also commonly found in meteorites,occur in the K/T boundary clay layer.

Question 43

Large meteorite impacts occur more frequently than small impacts.

Question 44

The relative numbers of incoming objects are not related to their size.

Question 45

Statistically,your risk of being killed by a meteoroid impact is greater than that of dying by flood or tornado.

Question 46

The biggest known impact on Earth in the twentieth century was the Tunguska,Siberia,event in1908.

Question 47

Estimating the magnitude of the K/T boundary impact earthquake can be done by scaling up from the energy released in nuclear explosions,leading to an estimate of a K/T impact earthquake of magnitude 11.3.

Question 48

A comet's tail results from the increased speed that a comet attains as it nears the Sun,leaving some particles behind because of the acceleration of the main mass of the comet.

Question 49

Small meteorite impacts create craters with central uplifts,while large impacts create craters with concave bottoms and no central uplifts.