wiki Root Word: Api-, Apo-, Aph-

Latin or Greek Meaning: Greek word that means "from, away from, asunder, separate, separation from, derived from." Usually used as a prefix.

Examples of words using "api-" that relate to space:

apoapsis: The point in the orbit of a body, such as a planet, moon, comet, or spacecraft which is furthest from the primary object. Special names, including aphelion and apogee are given to this orbital point for familiar systems.

apogee: The point in the orbit of the moon, or of an artificial satellite, most distant from the center of the Earth; The farthest, or highest, point; a culmination.

aphelion: The point in the orbit of a celestial body (such as a planet or comet) that is at the greatest distance from the Sun.

Other examples of words using "api-":

apothecary: A pharmacy, drugstore, or a place where medical prescriptions can be filled and stored. From Latin apotheca "storehouse"; which came from Greek apotheke "storehouse". Literally, "a place where things are put away", from apo- "away" + tithenai "to put".

This image shows an random object revolving around a more massive object.Apopasis is the point at which the less massive object is farthest away fromthe more massive object inits orbital path.

This image shows the location of apogee and perigee of a satellite orbiting the Earth.

SO WHAT??? SECTION:

The "api-/apo-" prefix can be helpful whenever describing the position of an object that revolves around another object. Since "apo/api" means away from, we can assume that any time a moon, planet, star, or other celectial object is described with a word that has "api" as a prefix, that means the object is the farthest away that it can get in its orbit. Apogee, aphelion, and apoapsis all describe this position, just talking about different objects. Apogee refers to the farthest an object gets from the Earth (remember that "geo" means Earth). Aphelion refers to the point in a planet's orbit when it is farthest from the Sun (helios is Greek for sun). Apoapsis is a much more general term that can be applied to ANY object revolving around a more massive object. Knowing this root word can thus be beneficial in figuring out what is being described in terms of orbital position.  

 Citations and Sources

Definition and examples of words using "api" came from the following wesbite:

"Latin-Greek Cross Reference: apo-, ap-, aph-." Robertson's Words for a Modern Age. 2007. Senior Scribe Publications . 9 May 2008 <http://wordinfo.info/words/index/info/view_unit/167/?letter=a&page=1&spage=1&s=apogee>

Apoapsis image and definition came from the following website:

Darling, David. "Celestial Mechanics: apoapsis." The Internet Encyclopedia of Science. The Worlds of David Darling. 12 May 2008 <http://www.daviddarling.info/encyclopedia/A/apoapsis.html>.

Apogee image came from this website:

Culp, Randy. "How Orbits Work." Boy Scouts Space Exploration Merit Badge. 20 Mar 2004. Randy Culp's Space Web. 14 May 2008 <http://my.execpc.com/~culp/space/orbit.html>.