extr - Feyn
- extragalactic objects
- extragalactic radio sources
- extrasolar planets
- extraterrestrial intelligence
- extraterrestrial life
- extraterrestrial matter
- extreme carbon stars
- extreme population I stars
- extreme ultraviolet radiation
- eyepieces
- F component
- F corona
- F dwarf stars
- F giant stars
- F layer
- F region
- F regions
- F stars
- F subdwarf stars
- F subgiant stars
- F supergiant stars
- F values
- Fabry Perot interferometers
- Fabry Perot spectrometers
- facilities
- faculae
- faint blue stars
- faint galaxies
- faint stars
- false color photography
- Fanaroff iley class
- far infrared radiation
- far ultraviolet radiation
- Faraday effect
- Faraday rotation
- fast Fourier transforms
- fast novas
- feed horns
