| Abbreviation | Definition |
|---|---|
| TAI | International Atomic Time (Temps Atomique International) |
| TAI | International Atomic Time (Temps Atomique International) [to 2015 July 1st, 35s ahead of UTC; from 2015 July 1st, 36s ahead of UTC.] |
| TAL | Teleskop Astronomi Lyubitel |
| TALC | The Astronomy Learning Center |
| TAMIA | Towards A More Inclusive Astronomy |
| TAMS | Terminal Age Main Sequence |
| TAOS | Taiwan American Occultation Survey |
| TARDIS | The Apparatus for Really Distant Interstellar Sojourns |
| TAU | Thousand Astronomical Unit |
| TBBT | The Big Bang Theory |
| TBC | Time Base Corrector |
| TCPA | Time for Closest Point of Approach |
| TDT | Terrestrial Dynamical Time |
| TESS | Transiting Exoplanet Survey Satellite |
| TGF | Terrestrial Gamma-Ray Flash |
| THAPA | Treasure Hunting in Astronomical Plate Archives |
| THS | Trimmable Horizontal Stabilizer |
| THSA | Trimmable Horizontal Stabilizer Actuators |
| TLE | Total Lunar Eclipse |
| TLP | The Lunascan Project |