Sidereal Time

• Sidereal Time follows the position of the stars and is an alternative to Solar Time which follows the position of the Sun. The Sidereal day is 4 minutes shorter than the Solar day. Both systems use hours, minutes and seconds.
• By using Sidereal Time, astronomers and navigators can locate celestial objects.

Definition

• Sidereal Time is defined as the Hour angle (measured in hours, minutes and seconds) of the observer’s meridian measured along the Celestial Equator to the Vernal Equinox.

Solar Time

• Solar Time is the angle between the observer’s longitude measured along the Equator to the Zero Meridian at Greenwich.
• The Stars and Planets are located in the night sky using Right Ascension and Declination relative to the Celestial Equator.
• This is the night sky equivalent of Latitude and Longitude on the Earth’s surface.