# parsecs and flies

**URL:** <https://boards.straightdope.com/t/parsecs-and-flies/257>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [October 20, 1999, 4:47pm UTC](https://boards.straightdope.com/t/parsecs-and-flies/257 "1999-10-20T16:47:00Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![woodja](https://avatars.discourse-cdn.com/v4/letter/w/ebca7d/32.png) [@woodja](https://boards.straightdope.com/u/woodja)\
**Post date:** [October 20, 1999, 4:47pm UTC](https://boards.straightdope.com/t/parsecs-and-flies/257/1 "1999-10-20T16:47:00Z")

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Not to be a critic, but I was reading through some old columns and noticed that in the "How to save earth from destruction: kill flies " column in Book 1, The Straight Dope, Cecil says that “The galaxy in which we presently reside, by way of comparison, is 25-30 parsecs across.” This is slightly inaccurate, insofar as the galaxy is actually about 100,000 parsecs across. A light year is 9.461x10^17 cm, while a parsec is 3.086x10^18 cm, so we see that a parsec (or unit of length equal to the distance at which a hypothetical star’s PARallax would be one SECond of arc) is about 3.28 light years. 50 of these is about 164 light years, or roughly 1/2,000 of the diameter of the Milky Way galaxy.  
Just for the record