Gamma Ray - The highest energy (shortest
wavelength) photons in the electromagnetic spectrum. Gamma rays
are often defined to begin at 10 keV, although radiation from
around 10 keV to several hundred keV is also referred to as hard
Geomagnetic Storm - A worldwide disturbance of the
Earth's magnetic field, associated with solar activity.
Geosynchronous Orbit - The orbit of a satellite that
travels above the Earth's equator from west to east so that it
has a speed matching that of the Earth's rotation and remains
stationary in relation to the Earth (also called geostationary).
Such an orbit has an altitude of about 35,900 km (22,300 miles).
GeV - billion electron volts (109)
Gluon - Current model of the atom in
which electrons are located in regions according to rules of
probability rather than in defined orbits.
Graviton - Carrier of the strong force which
binds quarks together in protons, neutrons, and other particles.
Gravity - A mass less particle whose
exchange between masses is thought to produce the gravitational
Galvanometer - Device used to measure very small
Gamma Decay - Process by which a nucleus emits
a gamma ray.
Particle - High energy photon emitted by a
Gas - State of matter that expands to
Geiger-Mueller Tube - Device used to detect radiation
using its ability to ionize matter.
General Theory of Relativity - Explanation of gravity and
accelerated motion invented by Einstein.
Grand Unified Theories - Theories being developed that
unify the stronger and electroweak forces into one force.
Gravitational Field - Distortion of space due to the
presence of mass.
Gravitational Force - Attraction between two objects
due to their mass.
Gravitational Mass - Ratio of gravitational force to
Gravitational Potential Energy - Change of energy of object when
moved in a gravitational field.
Graviton - Particle that carries the
gravitational force. Not yet observed.
Ground State - Lowest energy level of an
electron in an atom.
Grounding - Process of connecting a charged
object to Earth to remove objectís unbalanced charge.