Observing basics
恒星日
Sidereal day
One rotation relative to the stars, about 4 minutes short of a solar day.
That is why a given star rises about 4 minutes earlier each night.
Related terms
- Limiting magnitude — The faintest magnitude visible under current conditions.
- Apparent magnitude — Brightness as seen from Earth, not intrinsic output.
- Absolute magnitude — The magnitude an object would have at 10 parsecs.
- Altitude — Angle above the horizon: 0° at the horizon, 90° at zenith.