| Abbreviation | Definition |
|---|---|
| START | Solar Thermal Analysis Review and Training |
| STIS | Space Telescope Imaging Spectrograph |
| S-TYPE | Silicaceous (Asteroid) |
| SUN | Saturn, Uranus, and Neptune |
| SUPARCO | Space Uppar Atmosphere Research Commission |
| SUPARCO | Space & Uppar Atmosphere Research Commission |
| SVAA | Snake Valley Astronomical Association |
| SWAS | Submillimeter Wave Astronomy Satellite |
| SWYA | Scientific Writing for Young Astronomers |
| SXG | Spectrum- X- Gamma |
| SZA | Solar Zenith Angle |
| SZA | Sunyaev- Zel'dovich Array |
| SZE | Sunyaev-Zeldovich Effect |
| TAA | Tasmanian Amateur Astronomers |
| TAAA | Tucson Amateur Astronomy Association |
| TAAC | Temporary Astronomy and Astrophysics Center |
| TAAO | Tasmanian Amateur Astronomers On-line |
| TAAS | The Albuquerque Astronomical Society |
| TAC | Telescope Allocation Committee |
| TAC | The Astronomy Connection |