Orbs: The various aspects, or angular relationships, among the planets and points in a birth chart each come with their own orb -- the number of degrees by which they can stray from the accepted angle of an aspect and still be considered to have a viable, strong relationship with each other that will influence your life and personality.
For example, picture a 360-degree circle; this is the basic form of an astrological chart. A conjunction occurs when two planets are right next to each other in that chart, or nearly right on top of each other. Therefore, a conjunction is when two planets are zero degrees apart, or at the exact same point in that 360-degree circle.
But a conjunction has an orb of 10, which means those two planets can be up to ten degrees away from one another and still be considered in conjunction with each other, with all the attendant meanings and impacts.
Other aspects don’t have such a wide orb. A quincunx, for example, which occurs when two planets are 150 degrees apart, has an orb of only five -- meaning, the two planets can only deviate up to five degrees in either direction from that 150-degree point to still be considered a quincunx. Any farther apart, and astrologers won’t consider them to be in aspect to each other.
The orbs for the other major aspects are as follows: oppositions, ten; squares and trines, eight; and sextiles, five and quincunx three degrees.