| Iapetus |
The third largest moon of Saturn was discovered by Giovanni Cassini on October 25, 1671. Iapetus also is designated as "Saturn VIII". In Greek mythology, Iapetus was a Titan. |
| Ijiraq |
A moon of Saturn was discovered by the John Kavelaars in, 2000. Ijiraq also is designated as "Saturn XXII" and "S/2000 S6". In Inuit mythology, Ijiraq is a sort of boogeyman who captures children and hides them away forever. |
| Indus |
The constellation "The Indian" |
| Inferior Planet |
An Inferior Planet is a planet whose orbit lays inside the orbit of the Earth. These are: Mercury & Venus. |
| Interferometry |
A method for increasing resolving power by combining light obtained by two or more telescopes. |
| Io |
A moon of Jupiter was discovered by Galileo Galilei on January 7, 1610. Io is the innermost of the four Galilean moons and is also designated as "Jupiter I". In Greek mythology, Io was one of many of Zeus' lovers. |
| Iocaste |
A moon of Jupiter was discovered by Scott Sheppard and team in 2000. Iocaste is also designated as "Jupiter XXIV" and "S/2000 J3". In Greek mythology, Iocaste was he mother/wife of Oedipus. |
| Iris |
Thin overlapping plates which can be adjusted to change the diameter of a central opening. |
| Isonoe |
A moon of Jupiter was discovered by Scott Sheppard and team in 2000. Isonoe is also designated as "Jupiter XXVI" and "S/2000 J6". In Greek mythology, Isonoe was one of the Danaides and a lover of Zeus (Jupiter). |
