Fallout games have never really been put together particularly well, but that's what gives them a lot of their charm. Would Fallout New Vegas really be the same game if Doc Brown's head didn't creepily spin around from time to time, or if bodies didn't clip into the ground slightly and result in a horribly malformed ragdoll of a human being?
Basically, they're very buggy, which makes the fact that Fallout 3's sunlight has been secretly broken ever since launch not all that surprising.
First posted to the Fallout subreddit by user JBozART, it turns out that a minor error in Fallout 3's coding has meant that the sunlight in the game has actually been pointing in the wrong direction ever since the game was released back in 2008.
It's explained that a simple missing "-" in the game's coding essentially meant that the sunlight's y-axis wasn't inverted as originally intended, and that the sunlight has been out of line this entire time.
Of course, when you're traveling a Wasteland as inhospitable as Fallout 3's, you don't exactly have the time to ponder whether the sunlight is actually behaving as it should, hence why it's taken so long for this little coding error to be found.