The planetarium of Eise in Franeker runs continuously. This means that the planets are always in the position of the current date and time. This option is of course also available with the DMO, but in addition the DMO can go into constellation for any date entered.
Technology (for those who really want to know)
Each planet has its own computer. A stepper motor with accompanying driver is connected so the planet can be exactly positioned. Initial positioning is done with reed-switches that react to magnets on the track.
The position of the planet is calculated on a website which comes with the DMO. Each planet can read the output via WiFi and calculate where its place is on the planet orbit for the entered date and then "drive" to it.