| Abbreviation | Definition |
|---|---|
| SMASH | Survey of MAgellanic Stellar History |
| SMBH | Super Massive Black Hole |
| SMC | Small Magellanic Cloud |
| SML | Southern Major Lunar |
| SMOC | Science and Mission Operations Center |
| SMS | Sun, Moon, And Stars |
| SMVEMJSUNP | Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto |
| SNACS | Standard New Astronomy Cryostat For Sofia |
| SNII | SuperNova of Type II |
| SNR | Super Nova Remnant |
| SNY | Starry Night Backyard |
| SOAO | Sobaeksan Optical Astronomy Observatory |
| SOFA | Standards Of Fundamental Astronomy |
| SOFIA | Stratosferic Observatory for Infrared Astronomy |
| SOFIA | Stratospheric Observatory For Infrared Astronomy |
| SOLE | Sole Of Lemon Feet |
| SONO | South Node |
| SORAL | Steward Observatory Radio Astronomy Laboratory |
| SORCE | SOlar Radiation and Climate Experiment |
| SPACE | Systematic Planned Action of Consciousness and Energy |