Question 1

Assume that the average rate of 1- km sized asteroids hitting the Earth is about 1 every million years. The chance of the Earth being hit by a 1- km sized asteroid in the next 100 years is about:

Accepted Answer

A) inevitable, it has to happen sometime. 
B) zero. 
C) one in ten thousand. 
D) one in a million. 
E) one in 100 million.

Question 2

Which of the following does not lend support to the idea that Pluto is a Kuiper- belt object?

Accepted Answer

A) Pluto is smaller than many known comets, such as Halley's comet. 
B) Pluto has a comet- like composition and density. 
C) Pluto has a more eccentric orbit than other planets. 
D) Some known Kuiper- belt objects are hundreds of kilometers across. 
E) Some Kuiper- belt objects have their own moons.

Question 3

Briefly describe the evidence suggesting that a 10- km asteroid or comet hit Earth at the time of the dinosaur extinction.

Accepted Answer

The answer of Briefly describe the evidence suggesting that a...

Question 4

If we could put all the asteroids together, their total mass would be .

Accepted Answer

A) about the mass of Mercury 
B) greater than the mass of Earth but less than the mass of Jupiter 
C) much less than the mass of any terrestrial planet 
D) about the mass of Earth

Question 5

According to the nebular theory, how did the asteroid belt form?

Accepted Answer

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 is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets. 
C) It consists of objects that fragmented from the protosun during a catastrophic collision early in the formation of the solar system. 
D) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. 
E) It is made of planetesimals between the orbits of Mars and Jupiter that never formed into a planet.

Question 6

Rather than being a planet, Pluto is really just a large member of

Accepted Answer

A) the asteroid belt. 
B) the moon system around Neptune. 
C) the Oort cloud. 
D) the Kuiper belt. 
E) an extrasolar planetary system.

Question 7

An icy leftover planetesimal orbiting the Sun is

Accepted Answer

A) a comet. 
B) a meteorite. 
C) a meteor. 
D) an asteroid. 
E) possibly any of the above

Question 8

A typical shooting star in a meteor shower is caused by a entering Earth's atmosphere.

Accepted Answer

A) microscopic particle of interstellar dust 
B) pea- size particle from a comet 
C) boulder- size particle from a comet 
D) boulder- size particle from an asteroid 
E) pea- size particle from an asteroid

Question 9

What are "dwarf planets"?

Accepted Answer

The answer of What are "dwarf planets"?...

Question 10

Pluto's surface features are completely unknown and await the visit by the New Horizon's spacecraft in 2015.

Accepted Answer

A) True 
 B)False

Question 11

What do we mean by a primitive meteorite?

Accepted Answer

A) a piece of rock that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago 
B) a meteorite that fell to Earth at least 4 billion years ago 
C) a type of meteorite that is usually made mostly of high- density metals 
D) a meteorite that was discovered by primitive people

Question 12

A rocky leftover planetesimal orbiting the Sun is

Accepted Answer

A) a meteorite. 
B) a meteor. 
C) an asteroid. 
D) a comet. 
E) possibly any of the above

Question 13

Will Pluto eventually collide with Neptune?

Accepted Answer

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

Question 14

Suppose you find a meteorite made almost entirely of metal. According to current science, which of the following statements must be true?

Accepted Answer

A) Your meteorite was blasted off the surface of Mars by an impact. 
B) Your meteorite is a fragment of an object from the Kuiper belt. 
C) Your meteorite is a fragment from the core of a large asteroid that shattered in a collision. 
D) Radiometric dating will show the age of your meteorite to date to the formation of our solar system.

Question 15

According to the nebular theory, how did the Kuiper belt form?

Accepted Answer

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 between the orbits of Mars and Jupiter that never formed into a planet. 
C) It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet. 
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 formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets.

Question 16

During the time that a comet passes through the inner solar system, the comet can appear quite bright because

Accepted Answer

A) sunlight reflects off the comet's tail and coma. 
B) increasing friction causes the comet's nucleus to glow. 
C) sunlight reflects off the comet's nucleus. 
D) heat from the Sun causes the comet's nucleus to glow.

Question 17

How do asteroids differ from comets?

Accepted Answer

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

Question 18

Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they

Accepted Answer

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

Question 19

The total number of comets orbiting the Sun is estimated to be about .

Accepted Answer

A) 1 million 
B) 1 trillion 
C) 100,000 
D) 1,000

Question 20

A typical meteor is created by a particle about the size of a .

Accepted Answer

A) baseball 
B) pea 
C) basketball 
D) car

Exam 9: Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts