How long to travel one light year?

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wbd
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How long to travel one light year?

Post by wbd » Fri Oct 01, 2010 5:56 am

I'm just curious to know...
If a manned space flight were launched into outer space, how long would it take the rocket/capsule/module (sorry, not sure of the correct terminology) to travel one light year?

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Chris Peterson
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Re: How long to travel one light year?

Post by Chris Peterson » Fri Oct 01, 2010 6:11 am

wbd wrote:I'm just curious to know...
If a manned space flight were launched into outer space, how long would it take the rocket/capsule/module (sorry, not sure of the correct terminology) to travel one light year?
A typical higher achievable speed for a spacecraft is on the order of 20 km/s, or around 15,000 years to travel one light-year.

I doubt it would be manned on arrival!
Chris

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Re: How long to travel one light year?

Post by bystander » Fri Oct 01, 2010 6:36 am

Chris Peterson wrote:I doubt it would be manned on arrival!
Unless it was a generation ship.

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Re: How long to travel one light year?

Post by wbd » Fri Oct 01, 2010 6:48 am

15,000 years - wow!
Thanks for the responses.

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Re: How long to travel one light year?

Post by rstevenson » Fri Oct 01, 2010 12:14 pm

You might want to have a look at the Wikipedia page about Interstellar Travel. It's an eye opener, particularly the section on The difficulties of interstellar travel.

Rob

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Re: How long to travel one light year?

Post by RJN » Fri Oct 01, 2010 2:59 pm


Jassika2012
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Re: How long to travel one light year?

Post by Jassika2012 » Mon Jan 16, 2012 9:45 am

Hi,
I am a graduate and teaching in a college. My subjects were physics and maths a and maths b. As The light year is the distance that light covers in one year. And it is also used as a unit of distance.
so you can find it using this problem.
Time = 1 year (convert it into seconds)
Time= 1*365*24*60*60 seconds
I hope that you'll get satisfaction..? Please tell me if so...

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Re: How long to travel one light year?

Post by Jassika2012 » Thu Jan 19, 2012 10:33 am

Hi,
Did you get benefit or satisfaction form last post?

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neufer
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Re: How long to travel one light year?

Post by neufer » Thu Jan 19, 2012 3:46 pm

Jassika2012 wrote:
Did you get benefit or satisfaction form last post?
You might have mentioned how far light travels in one second.
Art Neuendorffer

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Ann
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Re: How long to travel one light year?

Post by Ann » Thu Jan 19, 2012 4:25 pm

neufer wrote:
Jassika2012 wrote:
Did you get benefit or satisfaction form last post?
You might have mentioned how far light travels in one second.
Ummm... how about a little less than 300,000 kilometers?
Click to play embedded YouTube video.
But there's no satisfying some people! :evil:

Ann
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Re: How long to travel one light year?

Post by Beyond » Thu Jan 19, 2012 4:55 pm

Ann, Ann, Ann, with your abilities with finding things on the internet and all you could come up with is Fake Stones :?: Tisk,Tisk,Tisk :!:
These guys are definately NOT satisfying :!: :!:
To find the Truth, you must go Beyond.

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Re: How long to travel one light year?

Post by Beyond » Thu Jan 19, 2012 5:04 pm

Ann, try this one. It even has the words. http://www.youtube.com/watch?v=3a7cHPy04s8
To find the Truth, you must go Beyond.

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Re: How long to travel one light year?

Post by Ann » Thu Jan 19, 2012 5:25 pm

Beyond wrote:Ann, try this one. It even has the words. http://www.youtube.com/watch?v=3a7cHPy04s8
:grovel: :grovel: :grovel:

:feeling almost satisfied:

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Re: How long to travel one light year?

Post by Beyond » Thu Jan 19, 2012 9:35 pm

Does this poodle help your 'satisfaction' at all :?:
dogs-dyed-fur-awkward-pet-photos.jpg
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Re: How long to travel one light year?

Post by Ann » Fri Jan 20, 2012 1:26 am




Think I prefer the cat! :D














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Re: How long to travel one light year?

Post by Beyond » Fri Jan 20, 2012 2:37 am

How about this cat?
blue-cat1.jpg
It's nose is a tad red, but that can be overlooked, right?
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Re: How long to travel one light year?

Post by Jassika2012 » Fri Jan 20, 2012 11:32 am

Hi,
This is a beautiful cat and the color of her nose is very attracting...hehe

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Re: How long to travel one light year?

Post by Jassika2012 » Fri Jan 20, 2012 1:54 pm

Hi,
It takes light (travelling at the speed of light, in a vacuum) one earth year to travel a light year, this is where the name comes from.
If something is travelling at less than the speed of light, it will take longer than an earth year.

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Re: How long to travel one light year?

Post 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! :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... :?: :( :?

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Re: How long to travel one light year?

Post by Chris Peterson » Fri Jan 20, 2012 6:54 pm

Ann wrote: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.
Hey, Ann, just do what I have kids in my classes do when they only have simple calculators with 8 or 10 digits- get rid of all the zeroes when you punch in the numbers, and then add them back in at the end. So a light year is just

6 [1] x 6 [1] x 24 x 365 x 3 [5] = 946080 [7] = 9,460,800,000,000

(9.5 trillion, which like you'd I'd typically memorize as 10 trillion for casual estimates- especially as the error bars on things at multiple light year distances in usually more than 5% anyway!) We're about the same age, meaning we learned to do math before handheld calculators existed. Did you learn to use a slide rule in school? The method of keeping zeroes in your head as you calculate is also used with that device.
Chris

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Re: How long to travel one light year?

Post by rstevenson » Fri Jan 20, 2012 7:25 pm

A note for those similarly bereft of modern calculators...

Last year I bought a TI-30XS calculator at my local office supply box for about $15. It has multi-line display, you can enter fractions as fractions, and (relative to this light-year issue) you can enter numbers using scientific notation so you can easily see the results. And if the results are still too big for the display, just scroll to the right using the scroll button.

It's a Good Thing(TM)

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Re: How long to travel one light year?

Post by geckzilla » Fri Jan 20, 2012 7:41 pm

I'm so lazy, I just ask Wolfram Alpha to calculate any of these things for me. Anything from what time it will be in 8 hours from now in Greece to these kind of questions.
http://www.wolframalpha.com/input/?i=Ho ... er+hour%3F
Just call me "geck" because "zilla" is like a last name.

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Re: How long to travel one light year?

Post by neufer » Fri Jan 20, 2012 7:45 pm

Art Neuendorffer

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Re: How long to travel one light year?

Post by Ann » Fri Jan 20, 2012 7:52 pm

Chris wrote:

Did you learn to use a slide rule in school?
I did, and I did okay at math in school, because I did my math homework since I wanted to have okay grades. But as soon as I had graduated, I decided that math and I would go our separate ways.
The method of keeping zeroes in your head as you calculate is also used with that device.
I don't remember how I used the slide rule, but your description of how to get rid of and then reinsert the zeroes was easy to understand, Chris.

Ann
Last edited by Ann on Fri Jan 20, 2012 8:10 pm, edited 1 time in total.
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Re: How long to travel one light year?

Post by Chris Peterson » Fri Jan 20, 2012 8:03 pm

geckzilla wrote:I'm so lazy, I just ask Wolfram Alpha to calculate any of these things for me. Anything from what time it will be in 8 hours from now in Greece to these kind of questions.
Don't you ever get an urge to know how many furlongs are in a light year, or how many license plates are possible in your state, when you're driving about and don't have a network connection? Then you're not a REAL geek! (I find myself running these kinds of calculations in my head when I'm out on a mountain somewhere, or otherwise out-of-touch and perhaps a bit bored. Just a couple of days ago, driving to Denver- 3 hours- I mentally worked out the size of cube it would take to store every human on Earth. These kinds of exercises keep the little gray cells in tune, and remind you of- or force you to rediscover- many nearly forgotten numerical tricks and shortcuts.)
Chris

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