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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.

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