# Thread: How many days in a year are ?

1. Look , i have got the following data from
wikipedia

1 light year ( distance travelled by light
in 1 year) = 9,460,730,472,580,800 metres
(exactly)
Speed of light = 299792458 metre/second (
exactly )
So time taken by light to travel a distance
of 1 light year will be
Time = Distance travelled / Time taken
= 9,460,730,472,580,800 /
299792458 Seconds
= 31557600 seconds
Now ,
1 Day = 24*60*60 seconds =
86400 seconds
so, 1 second = 1/86400 seconds
So , converting time taken by for
travelling in 1 light year into days will
give number of days in 1 year wich comes out
to be 31557600 / 86400 = 365.25
So according to this , a year should e
equal to 365.25 days
All I wanted to know is my presumption
right ? Because if you Google the above
question or convert 1 year into days with
Google, it will give the value of 365.242
days . So am i correct or Google is ?

PS - I asked the same question on yahoo answers and got some really ridiculous answers so I decided to aks in the science forum . So please provide some scientific explanation for your answers. Thanx

2.

3. I'm not entirely sure what your question is but it appears that you're confused about "year" as used in a light year and "year" as used on a calendar.
Perhaps if you'd carefully looked at the relevant Wikipedia entries:
Light year: As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year
So look at Julian year: 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.

In other words the "year" used for light years is a standardised measure that is defined ("arbitrarily") - NOT the "year" that's given by one orbit of Earth around the Sun (that being, of course, 365.242 days).

4. Originally Posted by saurabhkumarsingh
Look , i have got the following data from
wikipedia

1 light year ( distance travelled by light
in 1 year) = 9,460,730,472,580,800 metres
(exactly)
Speed of light = 299792458 metre/second (
exactly )
So time taken by light to travel a distance
of 1 light year will be
Time = Distance travelled / Time taken
= 9,460,730,472,580,800 /
299792458 Seconds
= 31557600 seconds
Now ,
1 Day = 24*60*60 seconds =
86400 seconds
so, 1 second = 1/86400 seconds
So , converting time taken by for
travelling in 1 light year into days will
give number of days in 1 year wich comes out
to be 31557600 / 86400 = 365.25
So according to this , a year should e
equal to 365.25 days
All I wanted to know is my presumption
right ? Because if you Google the above
question or convert 1 year into days with
Google, it will give the value of 365.242
days . So am i correct or Google is ?

PS - I asked the same question on yahoo answers and got some really ridiculous answers so I decided to aks in the science forum . So please provide some scientific explanation for your answers. Thanx
I don't know how to say it in English but the numbers get shortened... most of time especialy on internet...

5. Thanks buddy , I have just got the same result after searching it thoroughly on Wikipedia. So I got my question resolved myself. Thanks for the reply anyway.