[CentOS] What fires logrotate

I've been taking a look at how RedHat (and CentOS) handles logrotate.
According to the man page, logrotate is supposed to be fired by cron.
But when I look at root's crontab
   $ sudo crontab lu root
   no crontab for root

What exactly fires logrotate (and other scheduled events like
"logwatch", which ends up in root's inbox)?
   === Al