Chapter 12 Astronomy:)

A typical shooting star in a meteor shower is caused by a ________ entering Earth's atmosphere. A) pea-size particle from a comet B) microscopic particle of interstellar dust C) boulder- size particle from a comet D) pea-size particle from an asteroid E) boulder- size particle from an asteroid

A

How frequently do objects that threaten widespread devastation hit the Earth? A) about once every million years B) about once every year C) about once every thousand years D) about once every hundred million years

A

Kirkwood gaps in the asteroid belt occur at distances where A) the period of an orbiting asteroid would be a simple fraction (like 1/3 or 1/4) of Jupiter's orbital period. B) the period of an orbiting asteroid would be the same as Mars's orbital period. C) the density of asteroids is high enough for a large collision to pulverize a number of asteroids. D) the orbit would take the asteroid beyond the "frost line" in the solar system. E) the period of an orbiting asteroid would be the same as Jupiter's orbital period.

A

On average, how often do impacts large enough to produce mass extinction on the Earth occur? A) once every million years B) once in Earth's history C) once every thousand years D) once every century E) once every hundred million years

A

Rather than being a planet, Pluto is really just a large member of A) the Kuiper belt. B) the asteroid belt. C) an extrasolar planetary system. D) the Oort cloud. E) the moon system around Neptune.

A

What do astronomers mean when they refer to "gaps" in the asteroid belt between Mars and Jupiter? A) Asteroids seem to avoid certain orbits around the Sun, creating "gaps" in the orbits that asteroids can have. B) There are either pure metal or pure rock asteroids, but no mixtures. Thus there is a "gap" in the composition of asteroids. C) There are very few asteroids with diameters between 1 and 100 kilometers, creating a "gap" in the size distribution. D) There is a large population of asteroids too faint to see called the "gap" asteroids. E) Asteroids typically cluster together and this creates "gaps" on the sky.

A

What evidence led astronomers to conclude that the Oort cloud is a spherical distribution of comets? A) the observation that comets enter the solar system from random directions B) direct observation of comets orbiting the sun in the Oort cloud C) Astronomers did not draw that conclusion; the Oort cloud is shaped like a flat ring in the same plane as the planets.

A

What is a meteorite? A) a fragment of an asteroid from the solar system that has fallen to Earth's surface B) a comet that burns up in Earth's atmosphere C) a streak of light caused by a small particle from space burning up in Earth's atmosphere D) a streak of light caused by a star moving across the sky E) a small moon that orbits one of the giant planets

A

What part of a comet always points most directly away from the Sun? A) the plasma tail B) the coma C) the nucleus D) the dust tail E) the jets of gas

A

Where are the Trojan asteroids located? A) along Jupiter's orbit, 60° ahead of and behind Jupiter B) on orbits that cross Earth's orbit C) surrounding Jupiter D) on orbits that cross Mars's orbit E) in the center of the asteroid belt

A

According to the nebular theory, how did the Kuiper belt form? A) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system. B) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. C) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets. D) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet. E) It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula.

B

How do asteroids differ from comets? A) Asteroids are made of icy material. Comets are made of rocky material. B) Asteroids are made of rocky material. Comets are made of icy material. C) Asteroids and comets are both made of rocky and icy material, but asteroids are smaller in size than comets. D) Asteroids and comets are both made of rocky and icy material, but asteroids are larger in size than comets.

B

What is Eris? A) the largest moon of Saturn B) the largest known Kuiper Belt object C) the largest known asteroid D) Pluto's largest moon E) the largest known extrasolar planet

B

What is the approximate diameter of the largest asteroid? A) 10,000 km B) 1,000 km C) 10 km D) 100 km E) 1 km

B

What is the name of the largest known Kuiper Belt Object? A) Quaoar B) Charon C) Pluto D) Eris E) Sedna

B

What is the typical size of a comet's nucleus? A) 100 km B) 10 km C) 1000 km D) 1 meter E) Sizes are unknown because the nucleus is obscured by the coma.

B

What lucky factor prevented the Chelyabinsk object from causing much damage at ground level? A) It was made entirely of ices and thus exploded high in the air. B) It hit Earth at an oblique angle and thus exploded high in the air. C) A prototype asteroid defense system was being tested nearby.

B

Where did comets that are now in the Kuiper belt originally form? A) between the orbits of Jupiter and Neptune B) near the radius at which they orbit today C) inside Jupiter's orbit D) in the asteroid belt E) in the Oort cloud

B

Where did comets that are now in the Oort cloud originally form? A) outside Neptune's orbit B) near the jovian planets C) inside Jupiter's orbit D) within the solar nebula, but far outside the orbit of Pluto E) all of the above

B

Which of the following statements about comets and asteroids is true? A) Most of the trillions of comets in our solar system have tails. B) Comets are balls of ice and dust. C) All asteroids lie in the asteroid belt between Mars and Jupiter. D) Only asteroids collide with Earth. E) There are about 1 million known asteroids in the solar system.

B

Why aren't small asteroids spherical in shape? A) Large asteroids were once molten and therefore became spherical, but small asteroids were never molten. B) The strength of gravity on small asteroids is less than the strength of the rock. C) Small asteroids have odd shapes because they were all chipped off larger objects. D) Large asteroids became spherical because many small collisions chipped off pieces until only a sphere was left; this did not occur with small asteroids

B

Why do asteroids and comets differ in composition? A) Comets formed from the jovian nebula, while asteroids did not. B) Asteroids formed inside the frost line, while comets formed outside. C) Asteroids and comets formed at different times. D) Asteroids are much larger than comets. E) Comets are much larger than asteroids.

B

Why do we sometimes observe asteroids at the distances of the gaps in the asteroid belt? A) Actually, we never see asteroids in the gaps. B) A gap is located at an average orbital distance, and asteroid orbits often have large eccentricities. C) They are kept in place by shepherding asteroids. D) They are held in place by resonances with other asteroids. E) Jupiter's gravitational tugs keep them there.

B

Why was the Shoemaker-Levy 9 impact so important to astronomers? A) It wiped out the dinosaurs. B) It dredged up material that gave us our first direct look at Jupiter's interior composition. C) It was the first direct proof that impacts really occur. D) It was the first event in modern history that was brighter than the full moon in the sky. E) It confirmed our theory of solar system formation.

B

A rocky leftover planetesimal orbiting the Sun is A) a meteorite. B) a comet. C) an asteroid. D) a meteor. E) possibly any of the above

C

According to the nebular theory, how did the Oort cloud form? A) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet. B) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system. C) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets. D) It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula. E) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet.

C

An icy leftover planetesimal orbiting the Sun is A) a meteor. B) a meteorite. C) a comet. D) an asteroid. E) possibly any of the above

C

Comets with extremely elliptical orbits, like Hyakutake and Hale- Bopp, A) are captured by Jupiter. B) come from the asteroid belt. C) come from the Oort cloud. D) come from the Kuiper belt. E) are Trojan comets.

C

How many moons is Pluto known to have? A) two B) none C) three D) one E) four

C

If all the asteroids were gathered into a single object, it would make an object A) with enough mass to gather hydrogen and helium and become a gas giant. B) about the size of the Earth. C) about half the diameter of Earth's moon. D) about the size of Earth's moon.

C

Pluto is different from the Jovian planets in all of the following ways except which one? A) It is made mostly of ices. B) It doesn't have rings. C) It formed outside of the frost line in the solar nebula. D) It has a solid surface. E) Its orbit is not very close to being circular.

C

Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they A) contain a lot of iron and were used by humans to make iron tools. B) resemble the composition of Earth's core. C) contain a noticeable fraction of pure metallic flakes. D) resemble the composition of Earth's mantle. E) resemble the composition of rocks from lava flows that occurred on asteroids very shortly after the formation of the solar system.

C

What is Charon? A) one of the Galilean moons of Jupiter B) a moon of Neptune C) Pluto's largest moon D) the largest known comet E) the largest known asteroid

C

What was the Stardust mission? A) a mission to study the composition of an asteroid by hitting it with a massive object and observing the material thrown into space B) a mission to study the surface structure of a comet by dropping a lander onto its surface C) a mission to study the composition of a comet by collecting material from its tail and return that material to Earth D) a mission to study the outer planets of the solar system by sending a probe from one to the next with a wide variety of instruments

C

Which of the following is furthest from the Sun? A) Neptune B) an asteroid in the asteroid belt C) a comet in the Oort cloud D) a comet in the Kuiper belt E) Pluto

C

Will Pluto eventually collide with Neptune? A) Yes. B) No, because Pluto's orbit never comes anywhere close to Neptune's orbit. C) No, because the two planets have an orbital resonance that prevents them from colliding. D) No, because Pluto's orbit is completely outside Neptune's orbit. E) No, because Pluto's orbit is completely inside Neptune's orbit.

C

According to the nebular theory, how did the asteroid belt form? A) It is material left over from the interstellar cloud that never contracted with the rest of the gases to form the solar nebula. B) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system. C) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. D) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet. E) It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.

D

Approximately how long ago was Pluto discovered? A) about 25 years ago B) about 200 years ago C) about 2000 years ago D) about 75 years ago E) in ancient history

D

How do asteroids appear in long exposure images? A) as resolved disks, like the planets B) as complex curving and looping lines C) as points of light, like the stars D) as straight lines across a background of stars

D

How was Pluto's surface mapped? A) by imaging with the Hubble Space Telescope B) by mapping with the New Horizons spacecraft C) by imaging with powerful ground based telescopes D) by measuring the change in brightness as Charon eclipsed Pluto E) Pluto is too far away for its surface to be mapped.

D

If a major asteroid collision in the asteroid belt occurs, on average, 1 time in 100,000 years, then how many major collisions have occurred over the approximately 4 billion year history of the solar system? A) about 4 million B) about 4 billion C) about 4,000 D) about 40,000

D

Processed meteorites with high metal content probably are A) chunks of rock chipped off the planet Mercury. B) chunks of rock chipped off the planet Mars. C) pieces of comets rather than of asteroids. D) chunks of the core of a larger asteroid that was shattered by a collision. E) leftover chunks of rock from the earliest period in the formation of the solar system.

D

What do asteroids and comets have in common? A) They have similar orbital radii. B) They have similar densities. C) They have a similar range of orbital inclinations. D) Most are unchanged since their formation in the solar nebula. E) They have nothing in common with each other.

D

What happened to the "Impactor" of the Deep Impact mission? A) It blasted the comet apart, thus preventing a potential Earth collision. B) It blasted straight through the comet leaving a small hole. C) It missed the comet altogether. D) It created a small crater on the comet. E) It landed safely on the surface of the comet and returned material to Earth.

D

Which of the following are evidence for an asteroid impact being the cause of the extinction of the dinosaurs 65 million years ago as well as 75% of all species alive at the time)? A) no dinosaur fossils being present in rocks younger than 65 million years old B) a worldwide layer of the element iridium in 65 million year old rocks C) a buried crater more than 100 km across in the Gulf of Mexico D) all of the above

D

Why does the plasma tail of a comet always point away from the Sun? A) Radiation pressure from the Sun's light pushes the ions away. B) The conservation of the angular momentum of the tail keeps it always pointing away from the Sun. C) Gases from the comet, heated by the Sun, push the tail away from the Sun. D) The solar wind blows the plasma ions directly away from the Sun. E) It is allergic to sunlight.

D

In what way(s) has Pluto long been known to be different from the planets? A) It is far smaller than the terrestrial planets. B) Its orbit is more inclined to the ecliptic plane. C) It has a highly eccentric orbit. D) It is composed primarily of ices. E) All of the above

E

Meteorites can come from A) Mars. B) the cores of asteroids. C) the Moon. D) the crusts and mantles of asteroids. E) all of the above

E

What characteristic distinguishes a meteorite from a terrestrial rock? A) Meteorites have different isotope ratios of particular elements when compared to terrestrial rocks. B) Meteorites contain rare elements, such as iridium, that terrestrial rocks do not. C) A meteorite is usually covered with a dark crust from burning in Earth's atmosphere. D) A meteorite usually has a high metal content. E) All of the above are true.

E

What would be the consequence(s) of more frequent collisions between planets and asteroids? A) We would find more Martian meteorites on Earth. B) We would observe more meteor showers. C) Earth and other planets would have more large craters. D) A and B E) A and C

E

Which of the following does not lend support to the idea that Pluto is a Kuiper-belt object? A) Pluto has a comet-like composition and density. B) Pluto has a more eccentric orbit than other planets. C) Some known Kuiper-belt objects are hundreds of kilometers across. D) Some Kuiper - belt objects have their own moons. E) Pluto is smaller than many known comets, such as Halley's comet.

E