There are 32 main Nabhasa Yogas, which are classified in four categories.
The word Nabhasa means the sky. As such, the Yogas are formed in the sky with the help of all the three constituents, namely all the seven planets (excluding Rahu and Ketu), all the 12 signs and the 12 houses (including all shodhas vargas – 16 divisional charts), are called the Nabhasa Yogas. In these Yogas, all seven planets participate simultaneously. Each nativity will have at least one yoga out of 32 main Nabhasa Yogas.
The main question which arises is that why are only seven planets are considered and Rahu and Ketu are excluded ? There are fundamental reasons for excluding these two Chhaya Grahas (nodes of the moon). This aspect needs to be examined in some detail as it contains the key to understand the purpose and utility of the Nabhasa Yogas .
The Jeeva or the individual soul or self is in reality Pursha , who operates in this world through the causal, subtle and gross (physical) body. The causal body is the combination of soul and the mind (manah) – the sun and the Moon. This represents the creative principle in the Universe .The causal body is constituted of mere desires (Vasanas). Therefore this body is the seed of one’s personality in the unmanifested form. The causal body manifests and functions itself as the subtle (astral) body (the linga sareer), which operates with the help of five senses of perception represented by Mars, Mercury, Jupiter, Venus and Saturn. In other words, the subtle body is composed of feelings, emotions and thoughts generated on account of accumulated Vasanas from past births. Thus, the linga sareera represents the personality of an individual. This personality functions through the Gross body.
Nabhasa Yogas indicate basic traits and personality represented by the subtle body. The subtle body is like a sapling. It can be made to grow any way one likes. Similarly, the indications given by Nabhasa Yogas can be changed, modified or molded into any direction based on the vibration generated by the placement of Rahu and Ketu along with other Yogas in the nativity operating from time to time. The causal and subtle body operates through the Gross body. The gross body is like fully grown tree, which cannot be modified. As much, you can change or modify your feeling, emotions and thoughts manifesting in the Gross body, if you can control at the level of the subtle body, which supports the Gross body. Thus, Nabhasa Yogas contain and provide basic information that ultimately helps the individual to operate and use his own free will for the improvement of his lot.
Parasara narrated 32 Nabhasa Yogas. These are divided in four categories; there (3) are called Ashraya Yoga, two (2) Dala Yogas, twenty (20) Akriti Yoga and 7 (seven) Sankhya Yogas. These 32 Nabhasa Yogas again have 1800 different varieties (sub-divisions).
These numbers-32 and 1800 are of mystic nature as they represent subtle body (and not the gross body). The soul is immortal and never changes, it is the manah- mind that is responsible for the cycle of Birth and death, creation and destruction.
The Moon returns to the same point in the Zodiac in about 18.60 years, (which is the sidereal the period of Rahu and Ketu). If 32 is divided by number 1800, the remainder will always be 14. The number 14 represents 14 bhuvans(mansions) in which soul reappears as jeeva to exhaust his accumulated karma . Therefore, these numbers indicate the universal and immortal cycle of Karma.