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ch 14

typical shooting star in a meteor shower is caused by a ________ entering the earth's atmosphere.
pea-size particle from a comet
What do asteroids and comets have in common?
Most are unchanged since their formation in the solar nebula.
A rocky leftover planetesimal orbiting the Sun is
an asteroid
How does the largest asteroid, Ceres, compare in size to other solar system worlds?
It is about half the size of Pluto.
The combined mass of all the asteroids in the asteroid belt is
less than that of any terrestrial planet.
We know that there are large gaps in the average distances of asteroids from the Sun (within the asteroid belt) because we
have plotted distributions of the orbital radii of the asteroids.
The large gaps in the asteroid belt (often called Kirkwood gaps) are caused by
orbital resonances with Jupiter.
Why aren't small asteroids spherical in shape?
The strength of gravity on small asteroids is less than the strength of the rock.
Primitive meteorites can be distinguished from other meteorites and terrestrial rocks because they
contain a noticeable fraction of pure metallic flakes.
Most meteorites are
rocky and primitive.
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.
Comets with extremely elliptical orbits, like comets Hyakutake and Hale-Bopp,
come from the Oort cloud.
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
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
on average, how often do impactors about 10 km in size, large enough to produce mass extinction, hit the earth
once every hundred million years
All meteorites collected on Earth come from asteroids or comets.
Which of the following statements about comets and asteroids is true?
Comets are balls of ice and dust.
Why do asteroids and comets differ in composition?
asteroids formed inside the frost line, while comets formed outside.
What is the size of the largest asteroid
1,000 km
Where are the Trojan asteroids located
along Jupiter's orbit, 60° ahead of and behind Jupiter
Why isn't there a planet where the asteroid belt is located
Gravitational tugs from Jupiter prevented material from collecting together to form a planet.
What is a meteorite
a fragment of an asteroid from the solar system that has fallen to the earth's surface
What do we call a small piece of solar system
debris found on Earth?
What characteristic distinguishes a meteorite from a terrestrial rock?
All of the above are true.
Processed meteorites with high metal content probably are
chunks of a larger asteroid that was shattered by a collision.
Halley's comet is named after the English scientist Edmund Halley because he
calculated its orbit and predicted that it would return in 1758.
In order to have a comet named after you, you have to
be one of the first three discoverers who report it to the International Astronomical Union (IAU).
What part of a comet points most directly away from the Sun?
the plasma tail
When was Pluto discovered?
about 70 years ago
Why won't Pluto collide with Neptune?
The two planets have an orbital resonance that prevents them from colliding.
In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago, the dinosaurs (and over half of all the other species on the earth at that time) died off largely because
dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet.