Do homekit sunrise and sunset automations work without Internet?

We have a variety of devices controlled by automations that are triggered by sunrise or sunset. My hub is an ethernet-connected Apple TV 4k. I've verified that simple time-triggered automations work fine when my LAN can't get to the Internet (my eero mesh is fine but my ISP is down). But I haven't had a chance to see whether automations triggered by sunrise or sunset continue to work. Does my hub store some number of sunrise/sunset times? Or will these automations stop working?