Note:  Do not rely on this information. It is very old.

Radius Vector

Radius Vector is a line drawn from a centre of force to a body describing an orbit round that centre, and is a term of special application in astronomy, where it usually denotes the line drawn from the sun to the position of a planet at any time. It is obvious that this line is continually changing its length and direction.

“When the soul is once taken up with the things that are of absolute necessity, it will not be much troubled about other things.”
–Jeremiah Burroughs, The Rare Jewel of Christian Contentment