Parralax, Retrograde, all that Visual Brew-Ha-Ha

Parralax -- okaya parralax is the "apparent" (But not actual) movement of an object visually because of the REAL movement of the observer. Most common is the STellar parralax where a very distant (millions of miles) star appears to move, but realy it's the earth orbitting annually revolving around the sun that creates the impression of the star moving, a parallax. A large parralax angle means the star is closer. the farther away a star is (or an object is )from the observer, then the smaller the parralax angle (The smaller amount of shifter that occurs on the visual spectrum. A sundial is a perfect eample of a natural parralx (the dial moves (attached to the earth taht moves) creating hte impression that hte shadow moves. Just bottom-line, the observer (earth, or dial, or whatever) moves creating the impression that a distant objects moves. The closer the object, the larger the parallax angle.

Another well known parallax is the mercury retrograde. Note: this is mercury's apparent (not real) retrograde, that said, all apparent retrograde is really just a parallax effect. Mercury or Mars does not actually move backwards in the orbit. The earth just loops back around the sun so the vision the sun casts (From the earth) makes it look like it flips back the other way, In short, whenever the earth gets horizontal with a planet(it hten goes diagonal, given different rates of revoltion), the the parralax fliparound retrograde effect occurs.