The passage focuses on comets primarily in terms of their?

• orbital patterns

• coma and tails

• brightness

• size

The word "identical" in line I is closest in meaning to

• equally fast

• exactly alike

• near each other

• invisible

The word "heart" in line 4 is closest in meaning to?

• center

• edge

• tail

• beginning

Why does the author mention the Giotto probe in paragraph 3?

• t had a relatively small and inconspicuous nucleus.

• It was very similar to an asteroid.

• It was covered with an unusual black dust.

• It provided visual evidence of the makeup of a comet's nucleus.

It can be inferred from the passage that the nucleus of a comet is made up of

• dust and gas

• ice and dust

• hydrogen gas

• electrically charged atoms

The word "graphic" in line 9 is closest in meaning to?

• mathematical

• popular

• unusual

• vivid

Which of the following occurred as the ices from Halley's Comet evaporated?

• Black dust was left on the comet's surface.
  

• The nucleus of the comet expanded.
  

• The tail of the comet straightened out.

• Jets of gas caused the comet to increase its speed.

All of the following statements about the tails of comets are true EXCEPT:

• They can contain electrically charged or neutral particles.
  

• They can be formed only when there is sufficient heat.
  

• They are formed before the coma expands.

• They always point in the direction away from the Sun.

The word "distinct" in line 17 is closest in meaning to

• visible

• gaseous

• separate

• new

Compared to the tail of electrically charged atoms, the tail of neutral dust particles is relatively?

• long

• curved

• unpredictable

• bright