PDA

View Full Version : Posigrade/Prograde



Peter B
2001-Dec-27, 03:51 AM
After my masterful perilune/pericynthion question a little while ago, I now find myself faced with this little piece of uncertainty.

What's the difference between posigrade and prograde? Both seem to have retrograde as the antonym.

Argos
2001-Dec-27, 10:24 AM
What's the difference between posigrade and prograde? Both seem to have retrograde as the antonym.


When it comes to planets, prograde is the quality of the movement made west-east wise. It'is the direction of rotation of the planet Earth. It's also the direction of the orbits of all the planets.

The root "pro" means "forward", "in favor of", in Latin. Its antonym is "retro".

"Posi" is a root used to indicate a "positive" movement. "Positive", here, is a convention for the west-east movement. As you said, both prograde and posigrade have "retrograde" as antonym. To retain the orthodoxy, the antonym for posigrade should be "negagrade", an ugly word. So, it seems to me that "posigrade" is a rather "forced", defective, term.

Just to say that I personally prefer "prograde".

<font size=-1>[ This Message was edited by: Argos on 2001-12-28 11:34 ]</font>