spec - sphe
- special theory of relativity
- specific gravity
- specific intensity
- speckle interferometry
- speckles
- spectra
- spectral analysis
- spectral bands
- spectral classification
- spectral indices
- spectral line broadening
- spectral line formation
- spectral line shift
- spectral line splitting
- spectral line widths
- spectral lines
- spectral resolution
- spectral types
- spectrographs
