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Flashcards in The Universe and Objects Within Deck (23):

What is an achondrite?

a type of stony meteorite with no chondrules


What is an asteroid?

  • an object in orbit around the sun
  • intermediate in size between meteoroids and planets


What is a chondrite?

a type of meteorite that has a stony appearance and contains small spherical particles called chondrules


What is the coma of a comet?

the large gaseous region surrounding the nucleus


What is a comet?

  • a small body in the solar system
  • in orbit around the sun
  • has frozen material that vaporizes during the closer parts of its approach to the Sun to produce the characteristic tail


What are cosmic rays?

  • atomic nuclei and electrons that travel in space at very high speeds
  • most cosmic rays that are detected on Earth come from distant parts of the galaxy, but some come from the Sun, especially during its active phases


What is electromagnetic radiation?

radiation that transmits energy through periodic variations in its electric and magnetic force

includes radio waves, infrared and ultraviolet radiation, visible light, X-rays, and gamma rays.


What is the head of a comet?

  • the bright part of a comet
  • contains a small nucleus and its surrounding coma


What is the interstellar medium?

  • a mixture of ions, atoms, molecules, dust grains, cosmic rays, and magnetic fields
  • 99% gas, 1% dust by mass
  • extremely dilute


What is a meteor?

  • a glowing trail in the upper atmosphere
  • produced by a meteoroid burning up as it moves at high speed through dense air


What is a meteor shower?

numerous meteors seen in short time span

appears whenas the Earth passes through a cloud of meteoroids

usually remnants of a comet and still following the comet's orbit


What is a meteorite?

the remnant of meteoroid that has been partially eroded in passage through the Earth's atmosphere before hitting the surface


What is a meteoroid?

a large rock (but much smaller than minor planets) moving in an orbit in the solar system


What is a neutron?

a subatomic particle with mass similar to that of the proton but carrying no electric charge


What is a reflection nebula?

an interstellar cloud of gas and dust that is seen by the light which it reflects from nearby stars.


What is a satellite?

  • a body that revolves in orbit around another body
  • planets are satellites of the sun
  • the moon is a satellite of the earth
  • artificial satellites have been sent into orbit around the Earth, Moon, Mars and Venus


What is a solar nebula?

the gas and dust cloud remnant from which the sun, planets and other bodies of the solar system are thought to have formed


What is solar wind?

a flow of high-speed electrically charged particles from the solar corona outward through the solar system


What is a trojan asteroid?

asteroids that are in the same orbit as another body but do not collide with it because they precede or follow it by 60 degrees


Approximately how old is the universe?

roughly 14 billion years old


What is a chondrule?

a small round body (generally less than 1 mm) found in meteorites.


What is a bBreccia?

  • a type of rock composed of compacted fragments of other rocks
  • commonly produced by meteorite impacts on the lunar surface


What is an emission nebula?

an interstellar cloud of gas that has been ionized by energetic photons emitted by a star

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