flux - frin
- flux
- flux density
- focal length
- focal reducers
- focus
- Fokker Planck equation
- forbidden lines
- forbidden transitions
- Forbush effect
- force
- force of gravity
- forecasts
- fork mounting
- formation
- formation of elements
- formation of galaxies
- formation of stars
- four color photometry
- Fourier analysis
- Fourier components
- Fourier spectrometers
- Fourier transform spectroscopy
- Fourier transforms
- fragmentation
- fragments
- Fraunhofer lines
- free bound emission
- free free emission
- free free transition
- frequency
- frequency analysis
- frequency distribution
- frequency shift
- frequency standards
- friction
- Friedmann universe
