Hyperbolic - A trajectory path to a planet shaped like a hyperbola. Imbedded Satellite - A postulated class of satellites orbiting inside the rings, searched for but not found. The angle between the orbital plane of arevolving body and some fundamental plane, usually the plane of the celestial equator. Infrared - Electromagnetic radiation whose wavelength is longer than the longest visible red but shorter than radio waves. Interferometery - The location and examination of sources of electromagnetic radiation through the simultaneous use of two or more separated telescopes.
Interferometers produce overlapping wave patterns from the radiation.
These patterns are studied to determine the brightness and angular structure of the emitting source. Ion - An atom or molecular fragment that has a positive electrical charge due to the loss of one or more electrons. The simplest ion is the hydrogen nucleus, a single proton. IRIS - The Infrared Interferometer Spectrometer, one of the Voyager instruments. J Jet Propulsion - The engine moves forward by reacting to the momentum of air of gaseous material being forced out of the back of the engine.