by Ann » Fri Jan 20, 2012 4:51 pm
I've tried to calculate how many kilometers there are in one light-year many times, but my old solar-powered pocket calculator from the 1970s (which I got for free when I first subscribed to
Forskning och Framsteg, Research and Progress) just won't play along. It is able - just barely - to say that 60x60x24x365 is 31,536,000, so that there are 31,536,000 seconds in a year, but don't ask it to multiply that number by 300,000 kilometers. (Or else it is my number dyslectic brain cells that won't play along and do that sort of math. My cortex just sort of shuts down, I'm not kidding you.)
Good thing Wikipedia is back in action! According to
http://en.wikipedia.org/wiki/Light-year,
A light-year, also light year or lightyear (symbol: ly) is a unit of length, equal to just under 10 trillion kilometres (10×1015 metres, 10 petametres or about 6 trillion miles).
Well, fancy that! Something like 10,000,000,000,000 kilometers, then. That's good to know, if I can remember it.
Be careful, though, as you have to define "a year" properly in order to have a proper light-year.
http://en.wikipedia.org/wiki/Light-year wrote:
As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year.
According to
http://en.wikipedia.org/wiki/Julian_year_(astronomy),
In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of 86 400 SI seconds each, totaling 31 557 600 seconds.
That's good to know, particularly if I can remember it!
And hey, the tally of seconds in a year that I ordered my old solar-power pocket calculator to calculate was too low! It misplaced 21,600 seconds, making my light-year 21,600 x 300,000 kilometers too short! Then again, light doesn't travel fully 300,000 kilometers in one second, so maybe I got my light-year more or less correct after all... or not...
Ann
I've tried to calculate how many kilometers there are in one light-year many times, but my old solar-powered pocket calculator from the 1970s (which I got for free when I first subscribed to [i]Forskning och Framsteg[/i], Research and Progress) just won't play along. It is able - just barely - to say that 60x60x24x365 is 31,536,000, so that there are 31,536,000 seconds in a year, but don't ask it to multiply that number by 300,000 kilometers. (Or else it is my number dyslectic brain cells that won't play along and do that sort of math. My cortex just sort of shuts down, I'm not kidding you.)
Good thing Wikipedia is back in action! According to http://en.wikipedia.org/wiki/Light-year,
[quote]A light-year, also light year or lightyear (symbol: ly) is a unit of length, equal to just under 10 trillion kilometres (10×1015 metres, 10 petametres or about 6 trillion miles).[/quote]
Well, fancy that! Something like 10,000,000,000,000 kilometers, then. That's good to know, if I can remember it.
Be careful, though, as you have to define "a year" properly in order to have a proper light-year. http://en.wikipedia.org/wiki/Light-year wrote:
[quote]As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in a vacuum in one Julian year.[/quote]
According to http://en.wikipedia.org/wiki/Julian_year_(astronomy),
[quote]In astronomy, a Julian year (symbol: a) is a unit of measurement of time defined as exactly 365.25 days of 86 400 SI seconds each, totaling 31 557 600 seconds.[/quote]
That's good to know, particularly if I can remember it! :D
And hey, the tally of seconds in a year that I ordered my old solar-power pocket calculator to calculate was too low! It misplaced 21,600 seconds, making my light-year 21,600 x 300,000 kilometers too short! Then again, light doesn't travel fully 300,000 kilometers in one second, so maybe I got my light-year more or less correct after all... or not... :?: :( :?
Ann