Our Place in Space

The questions

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1. 1Which star is at the center of our solar system?

   1. A Polaris
   2. B The Sun
   3. C Sirius
   4. D Vega
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   B. The Sun

   The Sun supplies almost all the solar system's light and heat.

2. 2How many planets does our solar system have under the current classification?

   1. A Twelve
   2. B Nine
   3. C Eight
   4. D Six
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   C. Eight

   Mercury through Neptune make up the eight-planet list.

3. 3What name describes a planet's path around a star?

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   Orbit

   An orbit is the repeating path of one body around another.

4. 4Which unit is based on Earth's average distance from the Sun?

   1. A Solar mass
   2. B Light-second
   3. C Degree
   4. D Astronomical unit
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   D. Astronomical unit

   One astronomical unit, or AU, is about 150 million kilometers.

5. 5A light-year measures which quantity?

   1. A Mass
   2. B Time
   3. C Distance
   4. D Temperature
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   C. Distance

   It is the distance light travels in one year.

6. 6Which four planets are called terrestrial planets?

   1. A Mercury, Venus, Earth, and Mars
   2. B Venus, Jupiter, Saturn, and Neptune
   3. C Earth, Mars, Jupiter, and Saturn
   4. D Jupiter, Saturn, Uranus, and Neptune
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   A. Mercury, Venus, Earth, and Mars

   Terrestrial planets have rocky surfaces rather than giant gaseous envelopes.

7. 7Which force primarily holds the solar system together?

   1. A Air pressure
   2. B Gravity
   3. C Magnetism
   4. D Friction
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   B. Gravity

   The Sun's mass gives it the dominant gravitational influence here.

8. 8What term describes the space between stars?

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   Interstellar space

   Interstellar means between stars; interplanetary means between planets.

9. 9About how old is the solar system?

   1. A 4.6 billion years
   2. B 46 billion years
   3. C 4.6 million years
   4. D 46 thousand years
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   A. 4.6 billion years

   Rock dating and formation models place its beginning about 4.6 billion years ago.

10. 10What kind of cloud supplied the solar system's original material?

    1. A A ring of solid iron only
    2. B A cloud of pure oxygen
    3. C An existing system of fully formed planets
    4. D Gas and dust
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    D. Gas and dust

    The material collapsed and flattened into a disk around the young Sun.