- galactic
- Galactic
- Having to do with the galaxy. A galaxy is one of billions of large systems of stars and gas, held together by gravity, that make up the universe.
- gamma rays
- gamma ray
- Gamma rays
- Gamma ray
- A high energy photon, especially as emitted by a nucleus in a transition between two energy levels.
- GEC
- Geospace Electrodynamic Connections
- GEO
- Geostationary orbit
- Geoid
- geoid
- The surface within or around the earth that is everywhere perpendicular to the direction of gravity and coincides with mean sea level in the oceans at rest. Sea level of a moving ocean has topography, the topography that is measured by altimeter satellites to observe ocean currents.
- geospace
- Geospace
- The area of space surrounding the Earth but outside of the Earth's atmosphere - influenced by the particles and fields coming from the Sun.
- GEOSS
- Global Earth Observation System of Systems
- geostationary
- Geostationary
- Describes an orbit in which a satellite is always in the same position (appears stationary) with respect to the rotating Earth.
- GIS
- geographic information systems
- GLAST
- Gamma-ray Large Area Space Telescope
- GN
- Ground Network
- GNSS
- Global Navigation Satellite Systems
- GPM
- Global Precipitation Measurement
- GPS
- global positioning system
- GRACE
- Gravity Recovery and Climate Experiment
- GSRP
- Graduate Student Researchers Program
- Gyre
- gyre
- A great, circular motion of water in each of the major ocean basins centered on subtropical high-pressure region, with circulation clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.