Longer years.

[wildwood]

I believe every year is getting a tiny but increasing amount longer. Is this due to the sun getting cooler and thus having slightly less gravitational pull, or what?

[fo3nix]

Technically, yes.

If you define a year as one rotation of the Earth around the Sun, such that closer to the Sun would result in a shorter year and father away from the Sun a longer year.

The Sun is constantly losing its gravitational force.

However, it's by such a small amount each time, that it's negligible.

I have no idea on the numbers, but I'd think something like a millisecond every few years.

[heathfield]

The main cause of the Earth's rotation slowing is the friction produced by the oceanic tides. There's a (very!) detailed explanation here