Ch. 9 Reading Quiz
Which is closest to the average distance between asteroids in the asteroid belt?
1 million km
What is the typical size of comets that enter the inner solar system?
10 km
How do asteroids differ from comets?
Asteroids are made of rocky material. Comets are made of icy material
Why do asteroids and comets differ in composition?
Asteroids formed inside the frost line, while comets formed outside
How was Pluto's surface mapped?
By measuring the change in brightness as Charon eclipsed Pluto
Which of the following statements about comets and asteroids is true?
Comets are balls of ice and dust
Why was the Shoemaker-Levy 9 impact so important to astronomers?
It dredged up material that gave us our first direct look at Jupiter's interior composition
According to the nebular theory, how did the Oort cloud form?
It is made of planetesimals formed in the outer solar system that were flung into distant orbits by encounters with the jovian planets
According to the nebular theory, how did the Kuiper belt form?
It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet
Pluto is different from the Jovian planets in all of the following ways except which one?
Its surface temperature is very cold
What do asteroids and comets have in common?
Most are unchanged since their formation in the solar nebula
Which of the following does not lend support to the idea that Pluto is a Kuiper-belt object?
Pluto is smaller than many known comets, such as Halley's comet
What is Charon?
Pluto's largest moon
What happened in the Deep Impact mission?
The impactor created a small crater on the comet
Why does the plasma tail of a comet always point away from the Sun?
The solar wind blows the ions directly away from the Sun
Why aren't small asteroids spherical in shape?
The strength of gravity on small asteroids is less than the strength of the rock
Why won't Pluto collide with Neptune?
The two planets have an orbital resonance that prevents them from colliding
An icy leftover planetesimal orbiting the Sun is
a comet
Which of the following is furthest from the Sun?
a comet in the Oort cloud
What is a meteorite?
a fragment of an asteroid from the solar system that has fallen to Earth's surface
Processed meteorites with high metal content probably are
chunks of a larger asteroid that was shattered by a collision
Comets with extremely elliptical orbits, like comets Hyakutake and Hale-Bopp,
come from the Oort cloud
Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they
contain a noticeable fraction of pure metallic flakes
Meteorites can come from a) the cores of asteroids b) the Moon c) Mars d) ancient lava flows e) all of the above
e) all of the above
What characteristic distinguishes a meteorite from a terrestrial rock? a) A meteorite is usually covered with a dark crust from burning in Earth's atmosphere b) A meteorite usually has a high metal content c) Meteorites have different isotope ratios of particular elements when compared to terrestrial rocks d) Meteorites contain rare elements, such as iridium, that terrestrial rocks do not e) All of the above are true
e) all of the above are true
Where did comets that are now in the Oort cloud originally form?
near the jovian planets
Where did comets that are now in the Kuiper belt originally form?
near the radius at which they orbit today
On average, how often do impactors about 10 km in size, large enough to produce mass extinction, hit Earth?
once every hundred million years
A typical shooting star in a meteor shower is caused by a ________ entering Earth's atmosphere.
pea-size particle from a comet
Rather than being a planet, Pluto is really just a large member of
the Kuiper belt
