The hour is a unit of time and is a multiple of an SI base unit with the symbol hr.
There are 60 seconds in a minute and 60 minutes in an hour. Consequently, there are 3600 seconds in an hour.
In a mean solar day, there are 24 hours.
Originally in the Middle East, the hour was defined as 1/12 of the day or night time. However, seasonal factors clearly affected all of these definitions and an average is used today to normalise and allow calculations.
The sidereal minute is a unit of time used by astronomers and is derived from the SI unit system. We have used the symbol m-sr.
1 sidereal minute is made up of 60 sidereal seconds. This is derived ultimately from the sidereal day which is the time taken (in solar seconds) for the Earth to complete one rotation with respect to a distant star or constellation.