xkcd #2897: Light Leap Years ( imgs.xkcd.com )

Sibbo , 4 months ago

Why not redefine lightyears to include a leap year every four years. Except when the number ends on 00, but only if it is not divisible by 400. Physics would be so much easier!

Kecessa , 4 months ago (edited 4 months ago)

Well it’s in fact easy to calculate…

To make it easier to visualize we’ll start with year 400. From year 400 to year 799 you’ve got a leap year every 4 years except for years 500, 600, 700 and including year 400, so that’s 25 leap years for the first century and 24 for the others.

So you’ve got 25 + (3x24) = 97 leap years

And 75 + (3 x 76) = 303 non leap years

(97 x 366) + (303 x 365) = 146097 days every 400 years which means a year is 365.2425 days long on average.

365.2425 x 24 = 8765.82 hours on average

8765.82 x 60 x 60 = 31 556 952 seconds per year on average

31 556 952 x 299 792 458 (speed of light per second) = a light year is 9460536207068016 meters long or 9460536207068.016 km long when adjusted to take leap years into consideration.

Sibbo , 4 months ago

Okay, but now whenever you state one light year, it’s just a normal year. When you state four, it is three normal ones and one leap year. So four times one light year would not equal four light years.

Kecessa , 4 months ago (edited 4 months ago)

You asked for a lightyear adjusted based on leap years, I provided the number. It’s a bit more than 365 light days and a bit less than 366 light days, it’s closer to the real distance covered by light during the time the earth goes around the sun.

Edit: Don’t know why anyone would downvote me for providing what OP asked for in the first place, especially when their reply didn’t really make sense in the context…