A light year is a unit of distance (although not SI). So it would be 9.46 Pm, not 9.46 Pm/a (which is its speed, measured with the non-SI unit, a). Bill _____
Bill Potts W <http://wfpconsulting.com/> FP Consulting Roseville, CA <http://metric1.org/> http://metric1.org [SI Navigator] _____ From: [email protected] [mailto:[email protected]] On Behalf Of John M. Steele Sent: Sunday, March 29, 2009 07:43 To: U.S. Metric Association Subject: [USMA:44190] Re: The speed of light In my opinion, roundoff would be FAR less than our uncertainty in ANY interstellar distances. They are only known approximately. While a "light year" is about 9.46 Pm/a (depending on which "year" definition you use), that could probably be rounded to 10 with no great harm. Much like sea travel, you would have to frequently recalculate based on new observations. --- On Sun, 3/29/09, Jeremiah MacGregor <[email protected]> wrote: From: Jeremiah MacGregor <[email protected]> Subject: [USMA:44184] Re: The speed of light To: "U.S. Metric Association" <[email protected]> Date: Sunday, March 29, 2009, 9:28 AM Yes, you are right. I fixed it below. But either way the number in miles still never ends. I wonder what effect that would have if one was traveling to a distant galaxy using miles. Would the round off errors cause a problem in locating the planet? Jerry _____
