Sidereal Time

Timescale based on the rotation of the Earth relative to the fixed stars. 23h 56m (not as much as solar time, since the Earth needs to rotate slighly more to compensate for orbital distance travelled - 1° per day). This is effectively a complete rotation.

“More exactly, sidereal time is the angle, measured along the celestial equator, from the observer’s meridian to the great circle that passes through the March equinox and both celestial poles, and is usually expressed in hours, minutes, and seconds” - Wikipedia

• Stars will appear at the same point on the same sidereal time
• Solar time follows the sun, sidereal time follows the stars
• The March equinox itself precesses slowly westward relative to the fixed stars, completing one revolution in about 25,800 years. Handy video of the wobble here, helping visualize this: Vernal Equinox Precession
• Is actually 0.0084 seconds shorter than the stellar day, due to precession
• More on sidereal time and calculating it: Sidereal Time