Re: Fwd: Re: [office-formula] Straw poll - slug (and lightyear)

[robert_weir@us.ibm.com]

"David A. Wheeler" <dwheeler@dwheeler.com> wrote on 04/06/2010 05:33:46 
PM:
> 
> WARNING: Technical nitpick ahead:
> The distance light travels in a year, in a vacuum, *is* exact; the 
> meter is actually defined
> in terms of speed of light in a vacuum. And while an Earth year 
> isn't exactly 365.25 days, for purposes of a
> light-year, that's the exact value of the "year". It's not well-
> documented, but astronomers
> use this "standard year approximation" of 365.25 days when stating 
> light-years.
> And since a day is exactly 24*60*60 seconds, this has an exact value.
> I actually had to track that down, and I'm pretty sure I posted my 
citations
> (though I can't remember where they are right now).  If anyone knows
> differently,
> please let us know now.

That matches the International Astronomical Union's definition as well, 
only they say as distance light travels in a vacuum in 1 Julian Year, 
which is 365.25 days.

On the other hand, the IAU says Pluto is not a planet, so I don't know if 
we can trust them anymore.

-Rob