terrestrial dynamical time
Học thuậtThân thiện
A scientist uses terrestrial dynamical time to calculate the orbit of a satellite.
Definition
- Noun:
- A precise astronomical time scale: Terrestrial Dynamical Time (TDT) is a theoretical, uniform time scale defined by the orbital motion of the Earth around the Sun. It represents a continuous flow of time, free from the irregularities found in solar time.
- A corrected form of solar time: It is essentially mean solar time that has been adjusted to account for the small, predictable irregularities in the Earth's rotation and orbital motion.
Usage Examples
- Noun:
- The calculations for the satellite's trajectory require the precision of Terrestrial Dynamical Time.
- Astronomers use Terrestrial Dynamical Time as a stable reference for ephemerides.
Advanced Usage
- "Terrestrial Time" (TT): This is the modern term that has officially replaced "Terrestrial Dynamical Time." The two terms refer to the same continuous time scale.
- Since 1991, Terrestrial Time has been the standard for measuring astronomical events.
Variants and Related Words
- Terrestrial Time (TT): The successor and modern name for Terrestrial Dynamical Time.
- Ephemeris Time (ET): A predecessor time scale, which TDT was designed to refine and replace.
- International Atomic Time (TAI): The primary continuous time scale based on atomic clocks; Terrestrial Time is defined as TAI plus a fixed offset.
Synonyms
- Terrestrial Time (TT): The direct synonym and modern designation.
- Ephemeris Time (ET): A closely related, historical precursor time scale.
Related Terms and Context
- Dynamical Time: The broader category of time scales based on the laws of dynamics and planetary motions, of which Terrestrial Dynamical Time is a specific type.
- Barycentric Dynamical Time (TDB): A related time scale used for calculations where the center of the solar system (the barycenter) is the reference point, rather than the Earth's center.
A scientist uses terrestrial dynamical time to calculate the orbit of a satellite.
Noun
- (astronomy) a measure of time defined by Earth's orbital motion; terrestrial time is mean solar time corrected for the irregularities of the Earth's motions