| Abbreviation | Definition |
|---|---|
| JAP | Joint Astronomy Programme |
| JAXA | Japan Aerospace Exploration Agency |
| JBAA | Journal of the British Astronomical Association |
| JC | Jupiter Crosser |
| JCMT | James Clerk Maxwell Telescope |
| JCT | Jordan Cosmological Theory |
| JET | Journal Exaust Thruster |
| JFC | Jupiter family comets |
| JVO | Japanese Virtual Observatory |
| JWST | James Webb Space Telescope |
| KBO | Kuiper Belt Object |
| KD | Known Distance |
| KITP | Kavli Institute for Theoretical Physics |
| KM | KiloMetre |
| KP | Kitt Peak |
| kpc | kiloparsec = a unit of astronomical distance. |
| KVAS | Kanawha Valley Astronomical Society |
| LADC | Longitudinal Atmospheric Dispersion Compensator |
| LAMO | low altitude mapping orbit |
| LAMOI | Lithosphere, Asthenosphere, Mesosphere, Outer core, and Inner core |