@jesuscristo I mean, she didn't ask. But if you want an answer for your own curiosity, at a guess I'd assume it's because our calendar systems isn't accurate enough to make every single solstice line up perfectly with every actual earliest sunrise and stuff like that. This is probably exactly why we do leap years. Eventually things would slip really far off the general time frame they're supposed to be attached to if we weren't trying to slap it all back into place every so often.