Space and Solar Definitions - I

Inclination - The angular distance of the orbital plane from the plane of the planet's equator, stated in degrees.

Inferior conjunction - Alignment of Earth, sun, and an inferior planet on the same side of the sun.

Inferior planet - Planet which orbits closer to the Sun than the Earth's orbit.

Interplanetary Magnetic Field (Imf) - The magnetic field carried with the solar wind.

Ion - A charged particle consisting of an atom stripped of one or more of its electrons.

Ionosphere - The region of the earth's upper atmosphere containing a small percentage of free electrons and ions produced by photoioniza- tion of the constituents of the atmosphere by solar ultraviolet radiation at very short wavelengths (<1000 angstroms). The ionosphere significantly influences radiowave propagation of fre- quencies less than about 30 mhz.

Ionospheric Storm - A disturbance in the f region of the ionosphere, which occurs in connection with geomagnetic activity.

IPAC - Infrared Processing and Analysis Center at Caltech campus on Wilson Avenue in Pasadena.

IPC - Information Processing Center, JPL's computing center on Woodbury Avenue in Pasadena.

IR - Infrared, meaning "below red" radiation. Electromagnetic radiation in the neighborhood of 100 micrometers wavelength.

IRAS - Infrared Astronomical Satellite.

ISM - Interstellas medium.

ISO - International Standards Organization.

ISOE - Integrated Sequence of Events.

Isotropic - Having uniform properties in all directions.

IUS - Inertial Upper Stage.