Solar time

It's that time of the year again: last night, the clocks were turned back one hour to return back to the normal time. Despite all the effort and promises we don't deem to be getting rid of the daylight saving time anytime soon.

So what about the solar time? It's the apparent time derived from sun's movement across the sky. The apparent solar noon happens when the sun is at it's highest point in the sky. This can be observed by a stick: the shadow of the stick will point directly towards north/south depending on which hemisphere of the earth you happen to be, or if the sun is actually directly overhead there won't be a shadow at all.

When the sun has moved 15° in the sky an hour has passed. So even thought the degrees are divided in 60 minutes it actually takes only 4 minutes for the sun to move forward one degree.

In addition to the day not being exactly 24 hours this rapid movement of the apparent solar time is the reason why we stopped using it (it used to be common in the past, before railroads made it impractical). While we at where I currently live in Finland are now only 4 minutes ahead of the local solar time my original hometown, only couple of hundred kilometers east, is already 13 minutes ahead of us. Would be weird having to adjust the clocks almost a quarter hour every time we visit there.