Hannah: Twilight to twilight, actually (no Stephanie Meyer reference intended)... Also, technically not a "happy" day. Some of the more extremely ultra orthodox will beat themselves with willow switches and swing live chickens about the place (I'm not making this shit up. Look up the "Kapparot" ritual (It should be noted that swinging a bucket of KFC around your head does not count.)), and then all the priests will do the Spock thing for people during the Holy of Holies.
It's been about a decade since I lost my faith in the love of god, so I may have missed some of the finer details of the synagogue services.
The fun begins at the end where after telling god how sorry you've been for last year all day long, you then go and get absolutely wasted, stuff your face, supposedly read yourself some Mishna or Talmud and then, if you happen to be a chicken-swinger, go have sex with the missus through a hole in a sheet.