WordNet
n. (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 [syn: TT, terrestrial dynamical time, TDT, ephemeris time]
Wikipedia
Terrestrial Time (TT) is a modern astronomical time standard defined by the International Astronomical Union, primarily for time-measurements of astronomical observations made from the surface of Earth. For example, the Astronomical Almanac uses TT for its tables of positions ( ephemerides) of the Sun, Moon and planets as seen from Earth. In this role, TT continues Terrestrial Dynamical Time (TDT), which in turn succeeded ephemeris time (ET). TT shares the original purpose for which ET was designed, to be free of the irregularities in the rotation of Earth.
The unit of TT is the SI second, the definition of which is currently based on the caesium atomic clock, but TT is not itself defined by atomic clocks. It is a theoretical ideal, which real clocks can only approximate.
TT is distinct from the time scale often used as a basis for civil purposes, Coordinated Universal Time (UTC). TT indirectly underlies UTC, via International Atomic Time (TAI). Each leap second that is introduced into UTC causes UTC to diverge a little further from TT.
Usage examples of "terrestrial time".
It didn't surprise me a great deal to find recording-tapes in Belem's laboratory which described and localized a terrestrial time-axis.
For him, space takes on the aspect of time, because he is no longer able to retreat in it, just as you cannot step backward in terrestrial time—.
In their Terrestrial time they had dug long irrigation ditches with flint and wooden tools and turned the desert into a garden.
Rhodan wanted to wait till the technicians discovered what data the robots retained, but a preliminary examination revealed that the structure of the mechano-beings was so complicated that they would require at least a week in terms of Terrestrial time to finish their task.
Rhodan had called the object of their search Wanderer, Presumably this was a fitting definition for a celestial body returning once every two million years, terrestrial time, to the Vegan system unless it deviated from its course.
Ferrol, the eighth planet of the Vega system and the main world of an intelligent race, required barely twenty-four hours of Terrestrial time to put all available elements of its fleet into space.
In the hours that passed-days on the Terrestrial time scale-Tomisenkov had changed greatly.
Rachel walked into the hall and dropped her shoulder bag, blinking tiredly: it was still three in the morning by the shipboard time of the Gloriana even though it was two in the afternoon there in Geneva, and the cumulative effects of switching from the hundred-kilosecond diplomatic clock back to a terrestrial time zone was going to give her bad jet lag.