AST Chapter 9

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

All of the above are true.

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

Asteroids are made of rocky material. Comets are made of icy material.

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

Asteroids formed inside the frost line, while comets formed outside.

A spacecraft traveling through the asteroid belt has a high risk of being destroyed through a collision. True False

False

What is Charon? a moon of Neptune the largest known asteroid the largest known comet Pluto's largest moon one of the Galilean moons of Jupiter

Pluto's largest moon

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

The strength of gravity on small asteroids is less than the strength of the rock.

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

a fragment of an asteroid from the solar system that has fallen to Earth's surface

Approximately how long ago was Pluto discovered? about 2000 years ago about 75 years ago about 200 years ago in ancient history about 25 years ago

about 75 years ago

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

about once every million years

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

pea-size particle from a comet

What is Eris? Pluto's largest moon the largest known extrasolar planet the largest known Kuiper Belt object the largest moon of Saturn the largest known asteroid

the largest known Kuiper Belt object

What part of a comet always points most directly away from the Sun? the plasma tail the dust tail the coma the nucleus the jets of gas

the plasma tail