Astronomy Chapter 11 Flashcards
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Questions and Answers

Which of the following statements about comets and asteroids is true?

  • Asteroids are made of gas
  • Comets are balls of ice and dust (correct)
  • Comets are larger than asteroids
  • Asteroids are only found in the Oort cloud

    • What do asteroids and comets have in common?

    Most are unchanged since their formation in the solar nebula.

    How do asteroids differ from comets?

    Asteroids are larger in size than comets.

    A rocky leftover planetesimal orbiting the Sun is?

    <p>An asteroid.</p> Signup and view all the answers

    An icy leftover planetesimal orbiting the Sun is?

    <p>A comet.</p> Signup and view all the answers

    Why do asteroids and comets differ in composition?

    <p>Asteroids formed inside the frost line, while comets formed outside.</p> Signup and view all the answers

    Why aren't small asteroids spherical in shape?

    <p>The strength of gravity on small asteroids is less than the strength of the rock.</p> Signup and view all the answers

    What do astronomers mean when they refer to 'gaps' in the asteroid belt between Mars and Jupiter?

    <p>Asteroids seem to avoid certain orbits around the Sun, creating 'gaps' in the orbits that asteroids can have.</p> Signup and view all the answers

    What is a meteorite?

    <p>A fragment of an asteroid from the solar system that has fallen to Earth's surface.</p> Signup and view all the answers

    What characteristic distinguishes a meteorite from a terrestrial rock?

    <p>All of the above</p> Signup and view all the answers

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

    <p>Contain a noticeable fraction of pure metallic flakes.</p> Signup and view all the answers

    Meteorites can come from?

    <p>All of the above</p> Signup and view all the answers

    What part of a comet always points most directly away from the Sun?

    <p>The plasma tail.</p> Signup and view all the answers

    Where are the Trojan asteroids located?

    <p>Along Jupiter's orbit.</p> Signup and view all the answers

    Why does the plasma tail of a comet always point away from the Sun?

    <p>The solar wind blows the plasma ions directly away from the Sun.</p> Signup and view all the answers

    Where did comets that are now in the Oort cloud originally form?

    <p>Near the jovian planets.</p> Signup and view all the answers

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

    <p>It is made of planetesimals that formed beyond Neptune's orbit and never accreted to form a planet.</p> Signup and view all the answers

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

    <p>It formed outside of the frost line in the solar nebula.</p> Signup and view all the answers

    Processed meteorites with high metal content probably are?

    <p>Chunks that come from a shattered asteroid's core.</p> Signup and view all the answers

    What is Eris?

    <p>The largest known Kuiper Belt object.</p> Signup and view all the answers

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

    <p>Pea-size particle from a comet.</p> Signup and view all the answers

    What is the name of the largest known Kuiper Belt Object?

    <p>Eris.</p> Signup and view all the answers

    Which of the following statements about comets best describes the light we can observe?

    <p>A comet emits infrared light and reflects visible light.</p> Signup and view all the answers

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

    <p>Sunlight reflects off the comet's tail and coma.</p> Signup and view all the answers

    Pluto is most like a?

    <p>Comet.</p> Signup and view all the answers

    A rock found on Earth that crashed down from space is called ________.

    <p>A meteorite.</p> Signup and view all the answers

    The asteroid belt is located ________.

    <p>Between the orbits of Mars and Jupiter.</p> Signup and view all the answers

    Which direction do a comet's dust and plasma tails point?

    <p>Generally away from the Sun.</p> Signup and view all the answers

    When a comet passes near the Sun, part of it takes on the appearance of a large, bright ball from which the tail extends. This part is called ________.

    <p>The coma.</p> Signup and view all the answers

    Suppose there were no solar wind. How would the appearance of a comet in our inner solar system be different?

    <p>It would have only one tail instead of two.</p> Signup and view all the answers

    When we see a meteor shower, it means that ________.

    <p>Earth is crossing the orbit of a comet.</p> Signup and view all the answers

    Where did comets that are now in the Kuiper belt originally form?

    <p>Near the radius at which they orbit today.</p> Signup and view all the answers

    Which of the following is furthest from the Sun?

    <p>A comet in the Oort cloud.</p> Signup and view all the answers

    On average, how often do impacts large enough to produce mass extinction on the Earth occur?

    <p>Once every hundred million years.</p> Signup and view all the answers

    Which of the following statements is not true?

    <p>True</p> Signup and view all the answers

    What do we mean by a primitive meteorite?

    <p>A piece of rock that is essentially unchanged since it first condensed and accreted in the solar nebula some 4.6 billion years ago.</p> Signup and view all the answers

    Which statement is not thought to be true of all comets in our solar system?

    <p>True</p> Signup and view all the answers

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

    <p>Much less than the mass of any terrestrial planet.</p> Signup and view all the answers

    Why didn't a planet form where the asteroid belt is now located?

    <p>Gravitational tugs from Jupiter prevented material from collecting together to form a planet.</p> Signup and view all the answers

    A bit of matter that enters Earth's atmosphere and survives to reach the ground is called?

    <p>A meteorite.</p> Signup and view all the answers

    A meteor shower is produced when?

    <p>Earth passes through the orbital path of a comet.</p> Signup and view all the answers

    Most of the asteroids orbit the Sun in a belt between the orbits of?

    <p>Mars and Jupiter.</p> Signup and view all the answers

    Comets falling into the inner solar system from the ____ are called long-period comets.

    <p>Oort cloud.</p> Signup and view all the answers

    The gas tail of a comet always?

    <p>Points away from the Sun.</p> Signup and view all the answers

    The gas tail of a comet?

    <p>Is streaked and shows emission lines of ionized atoms.</p> Signup and view all the answers

    How is the coma of a comet produced?

    <p>Ices vaporize to become gas that form the coma around the comet.</p> Signup and view all the answers

    What characteristic of long-period comets suggests they come directly from the Oort cloud?

    <p>Their orbits have random inclinations with respect to the ecliptic plane.</p> Signup and view all the answers

    Which of the following is evidence for the connection between comets and meteor showers?

    <p>All of the above.</p> Signup and view all the answers

    Jupiter was probably influential in preventing the formation of a planet at the present location of the asteroid belt.

    <p>True</p> Signup and view all the answers

    Study Notes

    Comets and Asteroids

    • Comets are composed mainly of ice and dust, while asteroids are primarily rocky.
    • Both comets and asteroids are remnants from the solar nebula, remaining mostly unchanged since their formation.
    • Asteroids are typically larger than comets and are classified as rocky planetesimals orbiting the Sun, while comets are icy.

    Formation and Composition

    • Asteroids formed inside the frost line of the solar nebula; comets formed outside, leading to differences in composition.
    • Small asteroids lack a spherical shape due to the relatively weak force of gravity acting on them compared to the strength of the rocky material.

    Asteroid Belt and Meteorites

    • The asteroid belt lies between Mars and Jupiter, characterized by "gaps" where asteroids avoid certain orbits.
    • Meteorites are fragments of asteroids that have entered Earth’s atmosphere, distinguished by a noticeable fraction of metallic flakes in primitive meteorites.

    Cometary Features

    • A comet's plasma tail points directly away from the Sun due to solar wind and typically extends from the coma, which is the bright cloud surrounding the comet.
    • The Oort Cloud is where long-period comets originate, having formed near the jovian planets before being ejected to their current orbits.

    Kuiper Belt and Dwarf Planets

    • The Kuiper Belt comprises planetesimals that never coalesced into a planet, formed beyond Neptune's orbit.
    • Pluto is categorized as a large Kuiper Belt object rather than a planet, as it formed outside the frost line.

    Meteor Showers and Impact Events

    • Meteor showers occur when Earth crosses the orbit of a comet, with typical shooting stars resulting from pea-size particles.
    • Significant impact events capable of causing mass extinctions are estimated to occur once every hundred million years.

    Long-Period Comets

    • Long-period comets, with orbits that display random inclinations, are thought to originate from the Oort Cloud, reflecting their chaotic formation history.

    Jupiter's Influence

    • Jupiter's gravitational influence is crucial in preventing the formation of a planet in the asteroid belt by affecting the orbits of nearby material.

    Comet Behavior

    • When passing through the inner solar system, a comet appears bright due to sunlight reflecting off its coma and tail, which generally point away from the Sun.
    • If solar wind did not exist, a comet would display only one tail instead of two, since the gas tail depends on solar wind influence.

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    Test your knowledge of comets and asteroids with these flashcards based on Astronomy Chapter 11. Learn about their composition, similarities, and differences in an engaging and informative way.

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