Aspects or angles in a natal chart releases the energy pattern (good or difficult) between two or more planets. The aspects in a natal chart will never change.
The following is a short explanation of each aspect and orbs that are used.
The six major aspects between planets are:
Conjunction--------------------0 degrees (0-8 degree orb)
The keywords for a conjunction are INTENSITY, EMPHASIS and ACTIVITY. This aspect is the strongest of all the aspects. The conjunction can either be harmonious or difficult. The two planet's energies blend together emphasizing their powers and the activities of the house they are in. When a planet is within an 8 degree orb of the Ascendent (1st house cusp), the IC (4th house cusp), the Descendent (7th house cusp), or the MC (10th house cusp), the energy of that planet will reflect strongly in that house and the personality.
Square------------------------90 degrees (8 degree orb)
The square can be in the signs of cardinal which is Aries, Cancer, Capricorn and Libra.
The fixed signs of Leo, Aquarius, Taurus, and Scorpio.And the mutable signs of Gemini, Virgo, Pisces and Sagittarius. The trines and sextiles are nice to have, but it is the squares that provides the initiative to succeed.
Sextile------------------------60 degrees (6 degree orb)
Trine-------------------------120 degrees (8 degree orb)
OPPOSITION----180 degree orb (172-188 degrees) The keywords for this aspect is AWARENESS, BALANCE, CONFLICT. This major aspect is 180 degrees or opposite each other. The planets are six signs apart with six signs separating them. This is the widest aspect in a chart and reacts much as a seesaw does. It responds in a push-pull effect. The opposition teaches us to balance energies between the two planets. An opposition between planets is found to be involved in relationships.
Quincunx (Inconjunct)-----150 degrees (3 degree orb)
SEMI-SEXTILE----30 degree orb (28-32 degrees)The keywords to the semi-Sextile are COOPERATION, AGREEMENT, HARMONY. The play between two planets that are semi-sextile is less noticeable then the sextile of 60 degrees. But the aspect works much in the same way as a sextile, only with more of an involuntary or internal energy.
SEMI-SQUARE----45 degree orb (43-47 degrees) The keyword for a semi-square is TENSION or FRICTION. Again, the semi-square works much the same way as the square, only with less powerful energies.