Sidereal Time

Greenwich Mean Sidereal Time · itself a running clock

The clock astronomers actually keep — time measured against the distant stars rather than the sun. Because Earth moves along its orbit each day, a sidereal day runs 3m 56s short of a solar one, so star time gains a whole day on the calendar every year and any star returns to the same place at the same sidereal time all year round.

Does something here look wrong? Tell us about the Sidereal Time calendar.