Occurs when two or more planets are close together, usually less than 8º (sun and moon aspects about 10º). Those conjunctions that are less than 2º are considered to be very strong. The conjunction enhances the energy of two or more planets and creates a focal point in the chart. Conjunctions are considered the strongest of the aspects but with a variable energy.
The planets involved have to be taken into account, to see if the planets blend well together or not. Conjunctions with Jupiter, Venus, Moon and Sun tend to be easy aspects. While conjunctions with Saturn, Mars, Uranus and Pluto are hard aspects. Neptune and Mercury tend to be more neutral. For example a conjunction with the Moon and Venus will blend well and creates a great harmony but Saturn and Venus will not blend well as Saturn will limit Venus too much.
Conjunctions not only occur in the “natal” or birth chart but also can exist between two people. One person’s Sun may conjunct with another persons Moon thus creating a yin yang type bond or friendship. A final conjunction type is the transit where the current day planet aspects a planets on your natal chart. A common example is your birthday where the current year sun aspects your natal sun.