Planetary aspects are degrees of separation that create a contact between planets and points within an astrology chart and provide the astrologer with some of the most insightful and specific sources of information in a person's chart.

If you have your chart handy, take a look at it. What you have is a circle cut into 12 segments like a pie, and a number of glyphs which represent planets, around the edge of the circle. That circle can be broken up into 360 degrees, as can any circle. Imagine dividing that circle into 4 pieces of exactly the same size.  Divide 360 by 4 (the number of sides in a square), and you find that 1/4 of a circle is 90 degrees. This is the number of degrees in a Square aspect. This means that if two planets in your chart are approximately 90 degrees apart, they are in a square aspect.

The following table will give you the number of degrees in the 5 major aspects:    

There are many other aspects but these five provide most important indicators as well as being the ones with the strongest effects. It is rare for a person to have an exact aspect in their chart, that is, two planets which are separated by the exact number of degrees specified. The amount of variation or orb that is allowed for any particular aspect is a matter of much discussion among Astrologers; ultimately it boils down to personal preference. Some Astrologers use wide orbs, and others are more conservative, allowing only narrow orbs when they consider the nature of an aspect. There are also many factors that might expand or reduce an orb for a particular aspect. In other words, it isn't really possible to say exactly what number of degrees a person should consider when determining an aspect. You will note in many astrology reports it denotes if the orb is applying or separating. An applying orb is one where the planets are moving together and are in the process of creating a tighter aspect, a separating orb is one where the angle has already been exact and the planets are starting to move away from each other. Traditionally, applying orbs have more strength than separating orbs, although the exactness of the degree plays an important role in determining the overall strength of the influence.
 
As far as the aspects above are concerned, a good approximation of an allowable orb to use for the Conjunction, Square, Opposition and Trine would be 8 degrees. The average orb for a sextile, would be 5 degrees. In other words, using the square as an example, if two planets fall between 82 and 98 degrees apart from one another, you would consider them to be in a square aspect. As I hope I have made perfectly clear, these are only guidelines and can be modified depending on conditions. If you would prefer me to use specific orbs when drawing up an astrology chart for you just add a note to your order.

When considering the meaning of an aspect you must consider the nature of the planets involved as well as the aspect that they make to each other. For example, a square aspect between the Sun and Mars will mean something entirely different than a square between the Moon and Mars. Before you can determine the meanings of a particular aspect, you must really understand the meanings of each of the planets individually.  Looking at the five main aspects, the following is a good general explanation of the energy each aspect brings to a chart.

THE CONJUNCTION IN ASTROLOGY

A conjunction is a true blending of the energies of the planets involved.  While a conjunction is usually considered to be a positive aspect, there is a certain nebulous quality associated with it. It is not always easy for a person with a conjunction to recognize the qualities of the conjunction because the affects are so innate that the person who has them, sometimes fails to recognize them. It's as if the person with the conjunction is colorblind, and until they come to understand that their perception is in fact different than that of other people, they have no concept that there is anything peculiar or special about the way they see or experience reality. With the conjunction, more than any of the other aspects, it depends on the nature of the two (or more) planets involved whether the overall affect of the conjunction is positive or  negative, some planets such as Venus and Jupiter integrate wonderfully while others such as Pluto and Mars can make for a more troublesome pairing.

THE SQUARE IN ASTROLOGY

Squares are the most fundamental of the challenging aspects, there is an inner tension here that urges you to action. Two planets in square aspect are in some sort of conflict. Many times a person with a square aspect will jump back and forth between the planets involved, manifesting first one type of energy, then the other, but never seeming to get the two working together. Relating the two planets to each other is a constant struggle, which is why in the early days of Astrology, a square was considered to be an unfortunate aspect. This is because often a square will manifest as a problem which is seemingly without solution. And yet, if a person is faced with the same problem day after day, they may come up with a creative solution to that problem, one that makes the best use of the two energies and harnesses them together. The fact of the matter is that a square is a very dynamic aspect, one that spurs a person onward into motion. A square introduces the concept of resistance, so that no solution or compromise comes without some degree of struggle and hopefully growth.  A square cannot be ignored; it has to be dealt with effectively or the problem it represents will return again and again and again.  

THE OPPOSITION IN ASTROLOGY

Like Square, oppositions are also dynamic, however the energies while literally pulling in opposite directions seem to be a little easier to integrate than with the squares. This is like two (or more) people playing tug-of-war only the rope is YOU! Such concepts as polarity, strife and conflict are matched with other concepts like partnership and cooperation.  Oppositions are inducers of change because the person with an opposition is constantly confronted with two alternatives throughout their life.  Everything involving the two (or more) planets involved in the opposition is an ‘either or’ proposition. However,  unlike the square, the opposition seems to offer more opportunities for compromise. The conflict here, perhaps, because it is actually stronger than the square, is easier to recognize and perhaps that is why it becomes easier to resolve. Oppositions are really opposite to conjunctions in that they instill a certain degree of objectivity and insight that the conjunctions totally lack. Unlike the conjunctions which are so innate that the person may have trouble recognizing them, the opposition manifests in such a way that a person realizes quite early on how the opposition is manifesting in their life. Maybe it's because a person who is being pulled in two directions at once like a tug-of-war rope, experiences pain that makes it fairly obvious that something is going on.

THE TRINE IN ASTROLOGY

In traditional Astrology Squares were the bad guys and trines were not just the good guys, they were the darlings, the cosmic gift, the wonderful showers of talents and goodness raining from the heavens.

The fact of the matter is that as harmonious and flowing as trines can be, they do in fact have a downside as well. The problem with the great gifts and talents that a trine can bestow, is that these very talents are often taken for granted and not used and developed as they might be. Unlike a square or an opposition, a trine is rather passive by nature, and a person may just never get around to taking advantage of these great blessings. Trines, nor any other aspects for that matter, do not occur in a vacuum and often a planet that trines one planet will also be squaring or opposing another planet and this usually provides the extra push to develop the latent talent that the trine represents. Just remember that while you're gazing lovingly at your trines and counting your multitudinous blessings, talents that aren't used, aren't really talents at all.

THE SEXTILE IN ASTROLOGY

Sextiles are often considered to be little trines and are easy, creative and harmonious by nature, but less intensely wonderful than the trine. The sextile aspect involves dividing a circle into 6 parts, and the number 6 actually is the product of 2 x 3 - so it contains a bit of the trine and a bit of the opposition in it. It is therefore a little more dynamic than the trine, and is therefore more easily manifested and used by the person who has them in their chart.  The sextile suggests organization and ability in addition to the raw talent of the trine. Because there is a bit of a challenge implied in the sextile, the quality of the sextile lends itself more easily to the concept of an ‘Opportunity’ rather than an innate talent as with the trine. A person who is overly  blessed with sextiles might have the same sort of problems with expressing the talents as a person with many trines might.

Aspects, then, add a bit of spice to the lives of the planets in our chart.  Charts usually manifest many types of aspects and while a difficult square or opposition may tend to dominate the flavor of what is going on, but one mustn't focus entirely on the problems and challenges without giving oneself credit for the talents also represented. And it never hurts to remember that it takes challenge and sometimes struggle to manifest one's talents.