In Hindu astrology, it is known as Kala (dky).  It is an abstract idea.  It is measured in years, months, days, ghatis, palas and vipalas (also as years, months, days, hours, and seconds).  Actually, Sun does not revolve; it is stationary; it is the Earth, which revolves round its own axis as well as the Sun.  Days and nights are caused by the rotation of Earth on its axis.

1 day and night        = 60 ghatis

1 ghati        = 60 palas

1 pala        = 60 vipalas

1 day and night        = 60 ghatis

       = 24 Hours        

       = 24 x 60 minutes

Hence, 1 ghati        = 24 x 60 /60  =24 minutes

1 pala        = 24 seconds        

Nowadays, more and more people have started using hours, minutes and seconds instead of ghatis, palas and vipalas.  Even some of the panchangas (iapkax) are also giving the time both in ghatis and hours.