## Section Review

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### Vocabulary

astronomical unit | light year |

- The fastest plane can travel at about 4400 kilometers/hour. How long would
it take to travel to the Sun? Convert your answer to the number of days and
then the number of years. (The time it takes to travel a given distance =
(distance travelled)/speed, or in the notation used in the chapter:
*t = D/v*.)
- Compared to the distances between the planets in the solar system, how far
apart are the stars from each other? For this comparison find out how many
**astronomical units** there are between two typical stars (e.g., the Sun and
Proxima Centauri). Is the answer closer to 10, 100, 1000, 10000, 100,000, 500,000,
or 1,000,000?
- How far away is the nearest star outside of the solar system in kilometer
units and light year units?
- In a manner similar to how the light year is defined, define a ``car day''
as how far a car will travel in one day (24 hours) moving at a speed of 105
kilometers/hour (= 65 miles/hour). How far would a ``car day'' be in kilometers?
How many ''car days'' across is your home state (specify if it is the north-south
size or the east-west size)?
- How many kilometers would a light year be if it was discovered that the speed
of light was two times slower than previously thought?
- Where is our solar system in the Milky Way Galaxy?
- How old is the Earth compared to the age of the universe?
- How many times older is the Earth than the first civilizations?

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last updated: 03 May 2001

##### Is this page a copy of Strobel's
Astronomy Notes?

Author of original content:
Nick Strobel